PROOF.bend

bendtorch@1.1.1.0 · 812 lines · 0 definitions

1# The proofs of LAWS.bend. Every proof is plain Bend: no @unsafe, no ?TODO, no axioms. The arithmetic lemmas come
2# from bend-ml-nat-lemmas; the division lemmas behind gqa_head are llama.bend's (MIT, same author).
3
4import Base
5import bendtorch@1.1.1.0/main.bend as T
6import bendtorch@1.1.1.0/spec.bend as Spec
7import bendtorch@1.1.1.0/tensor.bend as TT
8import bendtorch@1.1.1.0/LAWS.bend as Laws
9import bend-ml-nat-lemmas@0.1.2.0/main.bend as NL
10import bend-ml-tensor-array@0.1.14.0/main.bend as TA
11
12# =====================================================================================================
13# Dot products
14# =====================================================================================================
15
16# dot(a + b, v) == dot(a, v) + dot(b, v): induction on the three vectors; at each entry (x + y)·z splits into x·z + y·z
17# (distributivity) and add4 regroups the four terms
18def dot_vadd(a: List<&2, Nat>, b: List<&2, Nat>, v: List<&2, Nat>) -> {Spec.dotn(Spec.vadd(a, b), v) == Nat.add(Spec.dotn(a, v), Spec.dotn(b, v)) : Nat}:
19  match a b v:
20    case Nil{} _ _:
21      {==}
22    case Con{+x, +xt} Nil{} +v:
23      Equal.sym(Nat, Nat.add(Spec.dotn(Con{x, xt}, v), 0n), Spec.dotn(Con{x, xt}, v), NL.add_zero(Spec.dotn(Con{x, xt}, v)))
24    case Con{x, xt} Con{y, yt} Nil{}:
25      {==}
26    case Con{+x, +xt} Con{+y, +yt} Con{+z, +zt}:
27      +xz = Nat.mul(x, z)
28      +yz = Nat.mul(y, z)
29      +pa = Spec.dotn(xt, zt)
30      +pb = Spec.dotn(yt, zt)
31      Equal.trans(Nat, Nat.add(Nat.mul(Nat.add(x, y), z), Spec.dotn(Spec.vadd(xt, yt), zt)), Nat.add(Nat.mul(Nat.add(x, y), z), Nat.add(pa, pb)), Nat.add(Nat.add(xz, pa), Nat.add(yz, pb)),
32        Equal.cong(Nat, Nat, s => Nat.add(Nat.mul(Nat.add(x, y), z), s), Spec.dotn(Spec.vadd(xt, yt), zt), Nat.add(pa, pb), dot_vadd(xt, yt, zt)),
33        Equal.trans(Nat, Nat.add(Nat.mul(Nat.add(x, y), z), Nat.add(pa, pb)), Nat.add(Nat.add(xz, yz), Nat.add(pa, pb)), Nat.add(Nat.add(xz, pa), Nat.add(yz, pb)),
34          Equal.cong(Nat, Nat, s => Nat.add(s, Nat.add(pa, pb)), Nat.mul(Nat.add(x, y), z), Nat.add(xz, yz), Equal.sym(Nat, Nat.add(xz, yz), Nat.mul(Nat.add(x, y), z), NL.mul_dist(x, y, z))),
35          NL.add4(xz, yz, pa, pb)))
36
37# dot(k·r, v) == k · dot(r, v): at each entry (k·x)·z == k·(x·z) (associativity), then k factors out of the sum
38def dot_scale(+k: Nat, r: List<&2, Nat>, v: List<&2, Nat>) -> {Spec.dotn(Spec.vscale(k, r), v) == Nat.mul(k, Spec.dotn(r, v)) : Nat}:
39  match r v:
40    case Nil{} _:
41      Equal.sym(Nat, Nat.mul(k, 0n), 0n, NL.mul_zero(k))
42    case Con{x, xt} Nil{}:
43      Equal.sym(Nat, Nat.mul(k, 0n), 0n, NL.mul_zero(k))
44    case Con{+x, +xt} Con{+z, +zt}:
45      +d = Spec.dotn(xt, zt)
46      Equal.trans(Nat, Nat.add(Nat.mul(Nat.mul(k, x), z), Spec.dotn(Spec.vscale(k, xt), zt)), Nat.add(Nat.mul(Nat.mul(k, x), z), Nat.mul(k, d)), Nat.mul(k, Nat.add(Nat.mul(x, z), d)),
47        Equal.cong(Nat, Nat, s => Nat.add(Nat.mul(Nat.mul(k, x), z), s), Spec.dotn(Spec.vscale(k, xt), zt), Nat.mul(k, d), dot_scale(k, xt, zt)),
48        Equal.trans(Nat, Nat.add(Nat.mul(Nat.mul(k, x), z), Nat.mul(k, d)), Nat.add(Nat.mul(k, Nat.mul(x, z)), Nat.mul(k, d)), Nat.mul(k, Nat.add(Nat.mul(x, z), d)),
49          Equal.cong(Nat, Nat, s => Nat.add(s, Nat.mul(k, d)), Nat.mul(Nat.mul(k, x), z), Nat.mul(k, Nat.mul(x, z)), Equal.sym(Nat, Nat.mul(k, Nat.mul(x, z)), Nat.mul(Nat.mul(k, x), z), NL.mul_assoc(k, x, z))),
50          Equal.sym(Nat, Nat.mul(k, Nat.add(Nat.mul(x, z), d)), Nat.add(Nat.mul(k, Nat.mul(x, z)), Nat.mul(k, d)), NL.mul_dist_l(k, Nat.mul(x, z), d))))
51
52# dot(a, b) == dot(b, a)
53def dot_comm(a: List<&2, Nat>, b: List<&2, Nat>) -> {Spec.dotn(a, b) == Spec.dotn(b, a) : Nat}:
54  match a b:
55    case Nil{} Nil{}:
56      {==}
57    case Nil{} Con{y, yt}:
58      {==}
59    case Con{x, xt} Nil{}:
60      {==}
61    case Con{+x, +xt} Con{+y, +yt}:
62      Equal.trans(Nat, Nat.add(Nat.mul(x, y), Spec.dotn(xt, yt)), Nat.add(Nat.mul(y, x), Spec.dotn(xt, yt)), Nat.add(Nat.mul(y, x), Spec.dotn(yt, xt)),
63        Equal.cong(Nat, Nat, s => Nat.add(s, Spec.dotn(xt, yt)), Nat.mul(x, y), Nat.mul(y, x), NL.mul_comm(x, y)),
64        Equal.cong(Nat, Nat, s => Nat.add(Nat.mul(y, x), s), Spec.dotn(xt, yt), Spec.dotn(yt, xt), dot_comm(xt, yt)))
65
66# =====================================================================================================
67# The linear laws
68# =====================================================================================================
69
70# PROOF (adjoint): induction on the rows of W and the entries of dy. Row r with weight g_i contributes g_i·(r·x) on the
71# left and (g_i·r)·x on the right (dot_scale); the right side's sum of weighted rows splits by dot_vadd.
72def Laws.adjoint(w, g, v):
73  match w g:
74    case Nil{} Nil{}:
75      {==}
76    case Nil{} Con{gi, gt}:
77      {==}
78    case Con{r, rt} Nil{}:
79      {==}
80    case Con{+r, +rt} Con{+gi, +gt}:
81      +a = Spec.dotn(Spec.vscale(gi, r), v)
82      +m = Spec.mtv(rt, gt)
83      Equal.trans(Nat, Nat.add(Nat.mul(gi, Spec.dotn(r, v)), Spec.dotn(gt, Spec.mv(rt, v))), Nat.add(Nat.mul(gi, Spec.dotn(r, v)), Spec.dotn(m, v)), Spec.dotn(Spec.vadd(Spec.vscale(gi, r), m), v),
84        Equal.cong(Nat, Nat, s => Nat.add(Nat.mul(gi, Spec.dotn(r, v)), s), Spec.dotn(gt, Spec.mv(rt, v)), Spec.dotn(m, v), Laws.adjoint(rt, gt, v)),
85        Equal.trans(Nat, Nat.add(Nat.mul(gi, Spec.dotn(r, v)), Spec.dotn(m, v)), Nat.add(a, Spec.dotn(m, v)), Spec.dotn(Spec.vadd(Spec.vscale(gi, r), m), v),
86          Equal.cong(Nat, Nat, s => Nat.add(s, Spec.dotn(m, v)), Nat.mul(gi, Spec.dotn(r, v)), a, Equal.sym(Nat, a, Nat.mul(gi, Spec.dotn(r, v)), dot_scale(gi, r, v))),
87          Equal.sym(Nat, Spec.dotn(Spec.vadd(Spec.vscale(gi, r), m), v), Nat.add(a, Spec.dotn(m, v)), dot_vadd(Spec.vscale(gi, r), m, v))))
88
89# PROOF (weight_adjoint): row by row, g_i·(r·x) == (g_i·x)·r, by dot_comm and dot_scale.
90def Laws.weight_adjoint(w, g, v):
91  match w g:
92    case Nil{} Nil{}:
93      {==}
94    case Nil{} Con{gi, gt}:
95      {==}
96    case Con{r, rt} Nil{}:
97      {==}
98    case Con{+r, +rt} Con{+gi, +gt}:
99      +f = Spec.frob(Spec.outer(gt, v), rt)
100      Equal.trans(Nat, Nat.add(Nat.mul(gi, Spec.dotn(r, v)), Spec.dotn(gt, Spec.mv(rt, v))), Nat.add(Nat.mul(gi, Spec.dotn(r, v)), f), Nat.add(Spec.dotn(Spec.vscale(gi, v), r), f),
101        Equal.cong(Nat, Nat, s => Nat.add(Nat.mul(gi, Spec.dotn(r, v)), s), Spec.dotn(gt, Spec.mv(rt, v)), f, Laws.weight_adjoint(rt, gt, v)),
102        Equal.cong(Nat, Nat, s => Nat.add(s, f), Nat.mul(gi, Spec.dotn(r, v)), Spec.dotn(Spec.vscale(gi, v), r),
103          Equal.trans(Nat, Nat.mul(gi, Spec.dotn(r, v)), Nat.mul(gi, Spec.dotn(v, r)), Spec.dotn(Spec.vscale(gi, v), r),
104            Equal.cong(Nat, Nat, s => Nat.mul(gi, s), Spec.dotn(r, v), Spec.dotn(v, r), dot_comm(r, v)),
105            Equal.sym(Nat, Spec.dotn(Spec.vscale(gi, v), r), Nat.mul(gi, Spec.dotn(v, r)), dot_scale(gi, v, r)))))
106
107# PROOF (adjoint_seq): adjoint once for W2 (with W1·x as the input), then once for W1.
108def Laws.adjoint_seq(w1, w2, g, v):
109  Equal.trans(Nat, Spec.dotn(g, Spec.mv(w2, Spec.mv(w1, v))), Spec.dotn(Spec.mtv(w2, g), Spec.mv(w1, v)), Spec.dotn(Spec.mtv(w1, Spec.mtv(w2, g)), v), Laws.adjoint(w2, g, Spec.mv(w1, v)), Laws.adjoint(w1, Spec.mtv(w2, g), v))
110
111# =====================================================================================================
112# Causal attention
113# =====================================================================================================
114
115# PROOF (seq_chain): Seq's forward pass computes W2·(W1·x) and saves x and W1·x; its backward pass computes
116# W1ᵀ·(W2ᵀ·dy). Every step of the combinator reduces, so this is adjoint_seq.
117def Laws.seq_chain(w1, w2, x, dy, g1, g2):
118  Laws.adjoint_seq(w1, w2, dy, x)
119
120# PROOF (fork_sum): Fork's backward pass is W1ᵀ·dy1 + W2ᵀ·dy2 (vadd, the add it was given); the dot of a sum is the sum
121# of the dots (dot_vadd), and each is its layer's adjoint law.
122def Laws.fork_sum(w1, w2, x, dy1, dy2, g1, g2):
123  Equal.trans(Nat, Nat.add(Spec.dotn(dy1, Spec.mv(w1, x)), Spec.dotn(dy2, Spec.mv(w2, x))), Nat.add(Spec.dotn(Spec.mtv(w1, dy1), x), Spec.dotn(Spec.mtv(w2, dy2), x)), Spec.dotn(Spec.vadd(Spec.mtv(w1, dy1), Spec.mtv(w2, dy2)), x),
124    Equal.trans(Nat, Nat.add(Spec.dotn(dy1, Spec.mv(w1, x)), Spec.dotn(dy2, Spec.mv(w2, x))), Nat.add(Spec.dotn(Spec.mtv(w1, dy1), x), Spec.dotn(dy2, Spec.mv(w2, x))), Nat.add(Spec.dotn(Spec.mtv(w1, dy1), x), Spec.dotn(Spec.mtv(w2, dy2), x)),
125      Equal.cong(Nat, Nat, z => Nat.add(z, Spec.dotn(dy2, Spec.mv(w2, x))), Spec.dotn(dy1, Spec.mv(w1, x)), Spec.dotn(Spec.mtv(w1, dy1), x), Laws.adjoint(w1, dy1, x)),
126      Equal.cong(Nat, Nat, z => Nat.add(Spec.dotn(Spec.mtv(w1, dy1), x), z), Spec.dotn(dy2, Spec.mv(w2, x)), Spec.dotn(Spec.mtv(w2, dy2), x), Laws.adjoint(w2, dy2, x))),
127    Equal.sym(Nat, Spec.dotn(Spec.vadd(Spec.mtv(w1, dy1), Spec.mtv(w2, dy2)), x), Nat.add(Spec.dotn(Spec.mtv(w1, dy1), x), Spec.dotn(Spec.mtv(w2, dy2), x)), dot_vadd(Spec.mtv(w1, dy1), Spec.mtv(w2, dy2), x)))
128
129def disc(b: Bool) -> Type:
130  match b:
131    case True{}:
132      Unit
133    case False{}:
134      Empty
135
136# False == True is impossible: rewriting the goal Empty = disc(False) with it gives disc(True) = Unit
137def false_true(e: {False{} == True{} : Bool}) -> Empty:
138  %Equal.sym(Bool, False{}, True{}, e) : disc(_)
139  Unit{}
140
141# xs reversed onto acc has the length of both
142def len_rcat(+xs: List<&2, F32>, +acc: List<&2, F32>) -> {List.length(&2, F32, T.rcat(xs, acc)) == Nat.add(List.length(&2, F32, xs), List.length(&2, F32, acc)) : Nat}:
143  match xs:
144    case Nil{}:
145      {==}
146    case Con{+x, +t}:
147      Equal.trans(Nat, List.length(&2, F32, T.rcat(t, x <> acc)), Nat.add(List.length(&2, F32, t), 1n+List.length(&2, F32, acc)), 1n+Nat.add(List.length(&2, F32, t), List.length(&2, F32, acc)), len_rcat(t, x <> acc), Equal.sym(Nat, 1n+Nat.add(List.length(&2, F32, t), List.length(&2, F32, acc)), Nat.add(List.length(&2, F32, t), 1n+List.length(&2, F32, acc)), NL.add_succ(List.length(&2, F32, t), List.length(&2, F32, acc))))
148
149# drow's row has the current dot, the m after it, and acc: 1 + m + |acc| numbers
150def len_drow(m: Nat, +hd: Nat, +ia: U32, +ib: U32, +bs: U32, +acc: List<&2, F32>, r: T.D2) -> {List.length(&2, F32, T.dr_row(T.drow(m, hd, ia, ib, bs, acc, r))) == Nat.add(1n+m, List.length(&2, F32, acc)) : Nat}:
151  match m r:
152    case 0n T.D2{a, b, +s}:
153      Equal.trans(Nat, List.length(&2, F32, T.rcat(s <> acc, Nil{})), Nat.add(1n+List.length(&2, F32, acc), 0n), 1n+List.length(&2, F32, acc), len_rcat(s <> acc, Nil{}), NL.add_zero(1n+List.length(&2, F32, acc)))
154    case 1n++p T.D2{a, b, +s}:
155      Equal.trans(Nat, List.length(&2, F32, T.dr_row(T.drow(p, hd, ia, (ib + bs : U32), bs, s <> acc, T.dot0(hd, ia, (ib + bs : U32), 1, 1, a, b)))), Nat.add(1n+p, 1n+List.length(&2, F32, acc)), 2n+Nat.add(p, List.length(&2, F32, acc)), len_drow(p, hd, ia, (ib + bs : U32), bs, s <> acc, T.dot0(hd, ia, (ib + bs : U32), 1, 1, a, b)), Equal.cong(Nat, Nat, z => 1n+z, Nat.add(p, 1n+List.length(&2, F32, acc)), 1n+Nat.add(p, List.length(&2, F32, acc)), Equal.sym(Nat, 1n+Nat.add(p, List.length(&2, F32, acc)), Nat.add(p, 1n+List.length(&2, F32, acc)), NL.add_succ(p, List.length(&2, F32, acc)))))
156
157# PROOF (causal_keys): qrow is drow(i, ..) from an empty accumulator, so its row has 1 + i + 0 numbers (len_drow).
158def Laws.causal_keys(i, hd, qs, qc, ks, kc, q, k):
159  Equal.trans(Nat, List.length(&2, F32, T.dr_row(T.qrow(i, hd, qs, qc, ks, kc, q, k))), Nat.add(1n+i, 0n), 1n+i, len_drow(i, hd, ((U32.from_nat(i) * qs : U32) + qc : U32), kc, ks, Nil{}, T.dot0(hd, ((U32.from_nat(i) * qs : U32) + qc : U32), kc, 1, 1, q, k)), NL.add_zero(1n+i))
160
161# n - 0 is n
162def sub0(+n: Nat) -> {Nat.sub(n, 0n) == n : Nat}:
163  match n:
164    case 0n:
165      {==}
166    case 1n+p:
167      {==}
168
169# the division loop of a softmax counts the 1 + k numbers it divides onto c (pr_of hands the count on as the row's)
170def cnt_div(q: Array<F32>, k: Array<F32>, kk: Nat, +idx: U32, +s: F32, +c: Nat, r: Array<F32> & F32) -> {T.pr_n(T.pr_of(q, k, T.pdiv(kk, idx, s, c, r))) == Nat.add(1n+kk, c) : Nat}:
171  match kk r:
172    case 0n Tuple{a, +x}:
173      {==}
174    case 1n++j Tuple{a, +x}:
175      Equal.trans(Nat, T.pr_n(T.pr_of(q, k, T.pdiv(j, (idx + 1 : U32), s, 1n+c, Array.get(F32, Array.set(F32, a, idx, (x / s : F32)), (idx + 1 : U32))))), Nat.add(1n+j, 1n+c), 2n+Nat.add(j, c), cnt_div(q, k, j, (idx + 1 : U32), s, 1n+c, Array.get(F32, Array.set(F32, a, idx, (x / s : F32)), (idx + 1 : U32))), Equal.cong(Nat, Nat, z => 1n+z, Nat.add(j, 1n+c), 1n+Nat.add(j, c), Equal.sym(Nat, 1n+Nat.add(j, c), Nat.add(j, 1n+c), NL.add_succ(j, c))))
176
177# the whole softmax over 1 + kk numbers reports 1 + kk, whatever max and exp found (they are matched, not computed)
178def cnt_psm3(q: Array<F32>, k: Array<F32>, +kk: Nat, +off: U32, r: T.AS) -> {T.pr_n(T.pr_of(q, k, T.psm3(kk, off, r))) == 1n+kk : Nat}:
179  match r:
180    case T.AS{a, +s}:
181      Equal.trans(Nat, T.pr_n(T.pr_of(q, k, T.pdiv(kk, off, s, 0n, Array.get(F32, a, off)))), Nat.add(1n+kk, 0n), 1n+kk, cnt_div(q, k, kk, off, s, 0n, Array.get(F32, a, off)), NL.add_zero(1n+kk))
182
183def cnt_psm2(q: Array<F32>, k: Array<F32>, +kk: Nat, +off: U32, r: T.AS) -> {T.pr_n(T.pr_of(q, k, T.psm2(kk, off, r))) == 1n+kk : Nat}:
184  match r:
185    case T.AS{a, +m}:
186      cnt_psm3(q, k, kk, off, T.pexp(kk, off, m, 0.0, Array.get(F32, a, off)))
187
188# pw writes xs and counts them from n; the softmax prow3 runs on them reports 1 + (|xs| + n - 1)
189def cnt_pw(+xs: List<&2, F32>, +idx: U32, +sc: F32, +n: Nat, +off: U32, q: Array<F32>, k: Array<F32>, p: Array<F32>) -> {T.pr_n(T.prow3(off, q, k, T.pw(xs, idx, sc, n, p))) == 1n+Nat.sub(Nat.add(List.length(&2, F32, xs), n), 1n) : Nat}:
190  match xs:
191    case Nil{}:
192      cnt_psm2(q, k, Nat.sub(n, 1n), off, T.pmax0(Nat.sub(n, 1n), off, Array.get(F32, p, off)))
193    case Con{+x, +t}:
194      Equal.trans(Nat, T.pr_n(T.prow3(off, q, k, T.pw(t, (idx + 1 : U32), sc, 1n+n, Array.set(F32, p, idx, (x * sc : F32))))), 1n+Nat.sub(Nat.add(List.length(&2, F32, t), 1n+n), 1n), 1n+Nat.sub(1n+Nat.add(List.length(&2, F32, t), n), 1n), cnt_pw(t, (idx + 1 : U32), sc, 1n+n, off, q, k, Array.set(F32, p, idx, (x * sc : F32))), Equal.cong(Nat, Nat, z => 1n+Nat.sub(z, 1n), Nat.add(List.length(&2, F32, t), 1n+n), 1n+Nat.add(List.length(&2, F32, t), n), Equal.sym(Nat, 1n+Nat.add(List.length(&2, F32, t), n), Nat.add(List.length(&2, F32, t), 1n+n), NL.add_succ(List.length(&2, F32, t), n))))
195
196# the count prow2 hands on for drow's row: 1 + m + |acc|, as len_drow, through cnt_pw
197def cnt_drow(m: Nat, +hd: Nat, +ia: U32, +ib: U32, +bs: U32, +acc: List<&2, F32>, r: T.D2, +sc: F32, +off: U32, pa: Array<F32>) -> {T.pr_n(T.prow2(sc, off, pa, T.drow(m, hd, ia, ib, bs, acc, r))) == Nat.add(1n+m, List.length(&2, F32, acc)) : Nat}:
198  match m r:
199    case 0n T.D2{a, b, +s}:
200      +rw = T.rcat(s <> acc, Nil{})
201      +la = List.length(&2, F32, acc)
202      Equal.trans(Nat, T.pr_n(T.prow3(off, a, b, T.pw(rw, off, sc, 0n, pa))), 1n+Nat.sub(Nat.add(List.length(&2, F32, rw), 0n), 1n), 1n+la, cnt_pw(rw, off, sc, 0n, off, a, b, pa),
203        Equal.cong(Nat, Nat, z => 1n+z, Nat.sub(Nat.add(List.length(&2, F32, rw), 0n), 1n), la,
204          Equal.trans(Nat, Nat.sub(Nat.add(List.length(&2, F32, rw), 0n), 1n), Nat.sub(1n+la, 1n), la,
205            Equal.cong(Nat, Nat, z => Nat.sub(z, 1n), Nat.add(List.length(&2, F32, rw), 0n), 1n+la,
206              Equal.trans(Nat, Nat.add(List.length(&2, F32, rw), 0n), List.length(&2, F32, rw), 1n+la, NL.add_zero(List.length(&2, F32, rw)),
207                Equal.trans(Nat, List.length(&2, F32, rw), Nat.add(1n+la, 0n), 1n+la, len_rcat(s <> acc, Nil{}), NL.add_zero(1n+la)))),
208            sub0(la))))
209    case 1n++p T.D2{a, b, +s}:
210      Equal.trans(Nat, T.pr_n(T.prow2(sc, off, pa, T.drow(p, hd, ia, (ib + bs : U32), bs, s <> acc, T.dot0(hd, ia, (ib + bs : U32), 1, 1, a, b)))), Nat.add(1n+p, 1n+List.length(&2, F32, acc)), 2n+Nat.add(p, List.length(&2, F32, acc)), cnt_drow(p, hd, ia, (ib + bs : U32), bs, s <> acc, T.dot0(hd, ia, (ib + bs : U32), 1, 1, a, b), sc, off, pa), Equal.cong(Nat, Nat, z => 1n+z, Nat.add(p, 1n+List.length(&2, F32, acc)), 1n+Nat.add(p, List.length(&2, F32, acc)), Equal.sym(Nat, 1n+Nat.add(p, List.length(&2, F32, acc)), Nat.add(p, 1n+List.length(&2, F32, acc)), NL.add_succ(p, List.length(&2, F32, acc)))))
211
212# PROOF (causal): prow runs prow2 on qrow's row, drow(i, ..) from an empty accumulator, so the count it hands the
213# softmax is 1 + i + 0 (cnt_drow).
214def Laws.causal(i, t, hd, sc, qs, qc, ks, kc, q, k, p):
215  Equal.trans(Nat, T.pr_n(T.prow(i, t, hd, sc, qs, qc, ks, kc, q, k, p)), Nat.add(1n+i, 0n), 1n+i, cnt_drow(i, hd, ((U32.from_nat(i) * qs : U32) + qc : U32), kc, ks, Nil{}, T.dot0(hd, ((U32.from_nat(i) * qs : U32) + qc : U32), kc, 1, 1, q, k), sc, (U32.from_nat(i) * U32.from_nat(t) : U32), p), NL.add_zero(1n+i))
216
217# gw writes xs and counts them from n: gr3 hands on |xs| + n (as cnt_pw for the forward pass)
218def cnt_gw(+xs: List<&2, F32>, +idx: U32, +n: Nat, +sc: F32, +off: U32, d: Array<F32>, v: Array<F32>, p: Array<F32>, g: Array<F32>) -> {T.gr_n(T.gr3(sc, off, d, v, p, T.gw(xs, idx, n, g))) == Nat.add(List.length(&2, F32, xs), n) : Nat}:
219  match xs:
220    case Nil{}:
221      {==}
222    case Con{+x, +t}:
223      Equal.trans(Nat, T.gr_n(T.gr3(sc, off, d, v, p, T.gw(t, (idx + 1 : U32), 1n+n, Array.set(F32, g, idx, x)))), Nat.add(List.length(&2, F32, t), 1n+n), 1n+Nat.add(List.length(&2, F32, t), n), cnt_gw(t, (idx + 1 : U32), 1n+n, sc, off, d, v, p, Array.set(F32, g, idx, x)), Equal.sym(Nat, 1n+Nat.add(List.length(&2, F32, t), n), Nat.add(List.length(&2, F32, t), 1n+n), NL.add_succ(List.length(&2, F32, t), n)))
224
225# the count gr2 hands on for drow's row: 1 + m + |acc|, as len_drow, through cnt_gw (cnt_drow's twin)
226def cnt_gdrow(m: Nat, +hd: Nat, +ia: U32, +ib: U32, +bs: U32, +acc: List<&2, F32>, r: T.D2, +sc: F32, +off: U32, pa: Array<F32>, ga: Array<F32>) -> {T.gr_n(T.gr2(sc, off, pa, ga, T.drow(m, hd, ia, ib, bs, acc, r))) == Nat.add(1n+m, List.length(&2, F32, acc)) : Nat}:
227  match m r:
228    case 0n T.D2{a, b, +s}:
229      +rw = T.rcat(s <> acc, Nil{})
230      Equal.trans(Nat, T.gr_n(T.gr3(sc, off, a, b, pa, T.gw(rw, off, 0n, ga))), Nat.add(List.length(&2, F32, rw), 0n), 1n+List.length(&2, F32, acc), cnt_gw(rw, off, 0n, sc, off, a, b, pa, ga),
231        Equal.trans(Nat, Nat.add(List.length(&2, F32, rw), 0n), List.length(&2, F32, rw), 1n+List.length(&2, F32, acc), NL.add_zero(List.length(&2, F32, rw)),
232          Equal.trans(Nat, List.length(&2, F32, rw), Nat.add(1n+List.length(&2, F32, acc), 0n), 1n+List.length(&2, F32, acc), len_rcat(s <> acc, Nil{}), NL.add_zero(1n+List.length(&2, F32, acc)))))
233    case 1n++p T.D2{a, b, +s}:
234      Equal.trans(Nat, T.gr_n(T.gr2(sc, off, pa, ga, T.drow(p, hd, ia, (ib + bs : U32), bs, s <> acc, T.dot0(hd, ia, (ib + bs : U32), 1, 1, a, b)))), Nat.add(1n+p, 1n+List.length(&2, F32, acc)), 2n+Nat.add(p, List.length(&2, F32, acc)), cnt_gdrow(p, hd, ia, (ib + bs : U32), bs, s <> acc, T.dot0(hd, ia, (ib + bs : U32), 1, 1, a, b), sc, off, pa, ga), Equal.cong(Nat, Nat, z => 1n+z, Nat.add(p, 1n+List.length(&2, F32, acc)), 1n+Nat.add(p, List.length(&2, F32, acc)), Equal.sym(Nat, 1n+Nat.add(p, List.length(&2, F32, acc)), Nat.add(p, 1n+List.length(&2, F32, acc)), NL.add_succ(p, List.length(&2, F32, acc)))))
235
236# PROOF (causal_grad): grow runs gr2 on drow(i, ..) from an empty accumulator, so the count is 1 + i + 0 (cnt_gdrow).
237def Laws.causal_grad(i, t, hd, sc, ds, dc, vs, vc, d, v, p, g):
238  Equal.trans(Nat, T.gr_n(T.grow(i, t, hd, sc, ds, dc, vs, vc, d, v, p, g)), Nat.add(1n+i, 0n), 1n+i, cnt_gdrow(i, hd, ((U32.from_nat(i) * ds : U32) + dc : U32), vc, vs, Nil{}, T.dot0(hd, ((U32.from_nat(i) * ds : U32) + dc : U32), vc, 1, 1, d, v), sc, (U32.from_nat(i) * U32.from_nat(t) : U32), p, g), NL.add_zero(1n+i))
239
240# =====================================================================================================
241# Attention's trees of sequences: parallel = sequential
242# =====================================================================================================
243
244# a ++ b == a2 ++ b2 from a == a2 and b == b2
245def app2(-A: Type, -a: List<&1, A>, -a2: List<&1, A>, -b: List<&1, A>, -b2: List<&1, A>, ea: {a == a2 : List<&1, A>}, eb: {b == b2 : List<&1, A>}) -> {List.append(&1, A, a, b) == List.append(&1, A, a2, b2) : List<&1, A>}:
246  Equal.trans(List<&1, A>, List.append(&1, A, a, b), List.append(&1, A, a2, b), List.append(&1, A, a2, b2), Equal.cong(List<&1, A>, List<&1, A>, z => List.append(&1, A, z, b), a, a2, ea), Equal.cong(List<&1, A>, List<&1, A>, z => List.append(&1, A, a2, z), b, b2, eb))
247
248# ---- the sequential map the tree is compared with: f(x) = fs_o(fheads(h, 0, dm, x)) for each x, in order ----
249
250def fmap(+h: Nat, +dm: T.Dm, xs: List<&1, T.FS>) -> List<&1, Array<F32>>:
251  match xs:
252    case Nil{}:
253      Nil{}
254    case Con{x, t}:
255      T.fs_o(T.fheads(h, 0n, dm, x)) <> fmap(h, dm, t)
256
257# ---- fleaf (the code's loop with an accumulator) is the map pushed onto the accumulator ----
258
259type L1R<-h: Nat, -dm: T.Dm, -xs: List<&1, T.FS>, -acc: List<&1, Array<F32>>> is Type:
260  L1R{ys: List<&1, T.FS>, same: {ys == xs : List<&1, T.FS>}, fact: {T.fleaf(xs, h, dm, acc) == List.reverse.go(&1, Array<F32>, acc, fmap(h, dm, xs)) : List<&1, Array<F32>>}}
261
262def l1_con(x: T.FS, -t: List<&1, T.FS>, +h: Nat, +dm: T.Dm, -acc: List<&1, Array<F32>>, r: L1R<h, dm, t, T.fs_o(T.fheads(h, 0n, dm, x)) <> acc>) -> L1R<h, dm, x <> t, acc>:
263  match r:
264    case L1R{ys, same, fact}:
265      L1R{x <> ys, Equal.cong(List<&1, T.FS>, List<&1, T.FS>, z => x <> z, ys, t, same), fact}
266
267def l1(xs: List<&1, T.FS>, +h: Nat, +dm: T.Dm, -acc: List<&1, Array<F32>>) -> L1R<h, dm, xs, acc>:
268  match xs:
269    case Nil{}:
270      L1R{Nil{}, {==}, {==}}
271    case Con{x, t}:
272      l1_con(x, t, h, dm, acc, l1(t, h, dm, T.fs_o(T.fheads(h, 0n, dm, x)) <> acc))
273
274# ---- the map of two lists appended is the two maps appended ----
275
276type MAR<-h: Nat, -dm: T.Dm, -a: List<&1, T.FS>, -b: List<&1, T.FS>> is Type:
277  MAR{ys: List<&1, T.FS>, same: {ys == a : List<&1, T.FS>}, fact: {fmap(h, dm, List.append(&1, T.FS, a, b)) == List.append(&1, Array<F32>, fmap(h, dm, a), fmap(h, dm, b)) : List<&1, Array<F32>>}}
278
279def ma_con(x: T.FS, -t: List<&1, T.FS>, +h: Nat, +dm: T.Dm, -b: List<&1, T.FS>, r: MAR<h, dm, t, b>) -> MAR<h, dm, x <> t, b>:
280  match r:
281    case MAR{ys, same, fact}:
282      MAR{x <> ys, Equal.cong(List<&1, T.FS>, List<&1, T.FS>, z => x <> z, ys, t, same), Equal.cong(List<&1, Array<F32>>, List<&1, Array<F32>>, z => T.fs_o(T.fheads(h, 0n, dm, x)) <> z, fmap(h, dm, List.append(&1, T.FS, t, b)), List.append(&1, Array<F32>, fmap(h, dm, t), fmap(h, dm, b)), fact)}
283
284def map_app(a: List<&1, T.FS>, +h: Nat, +dm: T.Dm, -b: List<&1, T.FS>) -> MAR<h, dm, a, b>:
285  match a:
286    case Nil{}:
287      MAR{Nil{}, {==}, {==}}
288    case Con{x, t}:
289      ma_con(x, t, h, dm, b, map_app(t, h, dm, b))
290
291# ---- a reversed onto b, then c appended: a reversed onto b ++ c ----
292
293type GAR<-a: List<&1, T.FS>, -b: List<&1, T.FS>, -c: List<&1, T.FS>> is Type:
294  GAR{ys: List<&1, T.FS>, same: {ys == a : List<&1, T.FS>}, fact: {List.append(&1, T.FS, List.reverse.go(&1, T.FS, a, b), c) == List.reverse.go(&1, T.FS, a, List.append(&1, T.FS, b, c)) : List<&1, T.FS>}}
295
296def ga_con(x: T.FS, -t: List<&1, T.FS>, -b: List<&1, T.FS>, -c: List<&1, T.FS>, r: GAR<t, x <> b, c>) -> GAR<x <> t, b, c>:
297  match r:
298    case GAR{ys, same, fact}:
299      GAR{x <> ys, Equal.cong(List<&1, T.FS>, List<&1, T.FS>, z => x <> z, ys, t, same), fact}
300
301def go_app(a: List<&1, T.FS>, -b: List<&1, T.FS>, -c: List<&1, T.FS>) -> GAR<a, b, c>:
302  match a:
303    case Nil{}:
304      GAR{Nil{}, {==}, {==}}
305    case Con{x, t}:
306      ga_con(x, t, b, c, go_app(t, x <> b, c))
307
308# ---- cut gives two halves that, appended, are acc reversed onto xs ----
309
310type CGR<-k: Nat, -xs: List<&1, T.FS>, -acc: List<&1, T.FS>> is Type:
311  CGR{hh: T.Halves<T.FS>, same: {hh == T.cut(T.FS, k, xs, acc) : T.Halves<T.FS>}, cat: {T.hcat(T.FS, hh) == List.reverse.go(&1, T.FS, acc, xs) : List<&1, T.FS>}}
312
313def cg_base(-k: Nat, xs: List<&1, T.FS>, -acc: List<&1, T.FS>, e: {T.cut(T.FS, k, xs, acc) == T.Halves{List.reverse(&1, T.FS, acc), xs} : T.Halves<T.FS>}, r: GAR<acc, Nil{}, xs>) -> CGR<k, xs, acc>:
314  match r:
315    case GAR{ys, +same, fact}:
316      CGR{T.Halves{List.reverse(&1, T.FS, ys), xs},
317        Equal.trans(T.Halves<T.FS>, T.Halves{List.reverse(&1, T.FS, ys), xs}, T.Halves{List.reverse(&1, T.FS, acc), xs}, T.cut(T.FS, k, xs, acc), Equal.cong(List<&1, T.FS>, T.Halves<T.FS>, z => T.Halves{List.reverse(&1, T.FS, z), xs}, ys, acc, same), Equal.sym(T.Halves<T.FS>, T.cut(T.FS, k, xs, acc), T.Halves{List.reverse(&1, T.FS, acc), xs}, e)),
318        Equal.trans(List<&1, T.FS>, List.append(&1, T.FS, List.reverse.go(&1, T.FS, ys, Nil{}), xs), List.append(&1, T.FS, List.reverse.go(&1, T.FS, acc, Nil{}), xs), List.reverse.go(&1, T.FS, acc, xs), Equal.cong(List<&1, T.FS>, List<&1, T.FS>, z => List.append(&1, T.FS, List.reverse.go(&1, T.FS, z, Nil{}), xs), ys, acc, same), fact)}
319
320def cg_con(-m: Nat, -x: T.FS, -t: List<&1, T.FS>, -acc: List<&1, T.FS>, r: CGR<m, t, x <> acc>) -> CGR<1n+m, x <> t, acc>:
321  match r:
322    case CGR{hh, same, cat}:
323      CGR{hh, same, cat}
324
325def cg(k: Nat, xs: List<&1, T.FS>, acc: List<&1, T.FS>) -> CGR<k, xs, acc>:
326  match k xs:
327    case 1n+m Con{x, t}:
328      cg_con(m, x, t, acc, cg(m, t, x <> acc))
329    case 0n ys:
330      cg_base(0n, ys, acc, {==}, go_app(acc, Nil{}, ys))
331    case 1n+m Nil{}:
332      cg_base(1n+m, Nil{}, acc, {==}, go_app(acc, Nil{}, Nil{}))
333
334# ---- the tree: fpar at depth d on two halves is the map of the halves appended ----
335
336type MR<-d: Nat, -gs: T.Halves<T.FS>, -n: Nat, -h: Nat, -dm: T.Dm> is Type:
337  MR{ys: List<&1, T.FS>, same: {ys == T.hcat(T.FS, gs) : List<&1, T.FS>}, fact: {T.fpar(d, gs, n, h, dm) == fmap(h, dm, T.hcat(T.FS, gs)) : List<&1, Array<F32>>}}
338
339# depth 0: the two leaves' loops, appended
340def m0c(-l: List<&1, T.FS>, -r: List<&1, T.FS>, -n: Nat, +h: Nat, +dm: T.Dm, -l1y: List<&1, T.FS>, +sl: {l1y == l : List<&1, T.FS>}, fl: {T.fleaf(l, h, dm, Nil{}) == fmap(h, dm, l) : List<&1, Array<F32>>}, r1: List<&1, T.FS>, sr: {r1 == r : List<&1, T.FS>}, fr: {T.fleaf(r, h, dm, Nil{}) == fmap(h, dm, r) : List<&1, Array<F32>>}, c: MAR<h, dm, l1y, r>) -> MR<0n, T.Halves{l, r}, n, h, dm>:
341  match c:
342    case MAR{l2, s2, fa}:
343      MR{List.append(&1, T.FS, l2, r1), app2(T.FS, l2, l, r1, r, Equal.trans(List<&1, T.FS>, l2, l1y, l, s2, sl), sr),
344        Equal.trans(List<&1, Array<F32>>, List.append(&1, Array<F32>, T.fleaf(l, h, dm, Nil{}), T.fleaf(r, h, dm, Nil{})), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), fmap(h, dm, List.append(&1, T.FS, l, r)), app2(Array<F32>, T.fleaf(l, h, dm, Nil{}), fmap(h, dm, l), T.fleaf(r, h, dm, Nil{}), fmap(h, dm, r), fl, fr),
345          Equal.sym(List<&1, Array<F32>>, fmap(h, dm, List.append(&1, T.FS, l, r)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)),
346            Equal.trans(List<&1, Array<F32>>, fmap(h, dm, List.append(&1, T.FS, l, r)), fmap(h, dm, List.append(&1, T.FS, l1y, r)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, List.append(&1, T.FS, z, r)), l, l1y, Equal.sym(List<&1, T.FS>, l1y, l, sl)),
347              Equal.trans(List<&1, Array<F32>>, fmap(h, dm, List.append(&1, T.FS, l1y, r)), List.append(&1, Array<F32>, fmap(h, dm, l1y), fmap(h, dm, r)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), fa, Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => List.append(&1, Array<F32>, fmap(h, dm, z), fmap(h, dm, r)), l1y, l, sl)))))}
348
349def m0b(-l: List<&1, T.FS>, -r: List<&1, T.FS>, -n: Nat, +h: Nat, +dm: T.Dm, l1y: List<&1, T.FS>, +sl: {l1y == l : List<&1, T.FS>}, fl: {T.fleaf(l, h, dm, Nil{}) == fmap(h, dm, l) : List<&1, Array<F32>>}, b: L1R<h, dm, r, Nil{}>) -> MR<0n, T.Halves{l, r}, n, h, dm>:
350  match b:
351    case L1R{r1, sr, fr}:
352      m0c(l, r, n, h, dm, l1y, sl, fl, r1, sr, fr, map_app(l1y, h, dm, r))
353
354def m0a(-l: List<&1, T.FS>, r: List<&1, T.FS>, -n: Nat, +h: Nat, +dm: T.Dm, a: L1R<h, dm, l, Nil{}>) -> MR<0n, T.Halves{l, r}, n, h, dm>:
355  match a:
356    case L1R{l1y, sl, fl}:
357      m0b(l, r, n, h, dm, l1y, sl, fl, l1(r, h, dm, Nil{}))
358
359# depth 1 + e: each half cut in two and its tree (the closures run main at depth e), then the two maps appended
360def m1c(-e: Nat, -l: List<&1, T.FS>, -r: List<&1, T.FS>, +n: Nat, +h: Nat, +dm: T.Dm, -hh1: T.Halves<T.FS>, s1: {hh1 == T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}) : T.Halves<T.FS>}, +cat1: {T.hcat(T.FS, hh1) == l : List<&1, T.FS>}, -hh2: T.Halves<T.FS>, s2: {hh2 == T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}) : T.Halves<T.FS>}, +cat2: {T.hcat(T.FS, hh2) == r : List<&1, T.FS>}, -y1: List<&1, T.FS>, sy1: {y1 == T.hcat(T.FS, hh1) : List<&1, T.FS>}, f1: {T.fpar(e, hh1, TA.half(n), h, dm) == fmap(h, dm, T.hcat(T.FS, hh1)) : List<&1, Array<F32>>}, y2: List<&1, T.FS>, sy2: {y2 == T.hcat(T.FS, hh2) : List<&1, T.FS>}, f2: {T.fpar(e, hh2, Nat.sub(n, TA.half(n)), h, dm) == fmap(h, dm, T.hcat(T.FS, hh2)) : List<&1, Array<F32>>}, ma: MAR<h, dm, y1, y2>) -> MR<1n+e, T.Halves{l, r}, n, h, dm>:
361  match ma:
362    case MAR{y1b, sb, fa}:
363      +ly1 = Equal.trans(List<&1, T.FS>, y1, T.hcat(T.FS, hh1), l, sy1, cat1)
364      +ly2 = Equal.trans(List<&1, T.FS>, y2, T.hcat(T.FS, hh2), r, sy2, cat2)
365      +q1 = Equal.trans(List<&1, Array<F32>>, T.fpar(e, T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}), TA.half(n), h, dm), T.fpar(e, hh1, TA.half(n), h, dm), fmap(h, dm, l), Equal.cong(T.Halves<T.FS>, List<&1, Array<F32>>, z => T.fpar(e, z, TA.half(n), h, dm), T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}), hh1, Equal.sym(T.Halves<T.FS>, hh1, T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}), s1)), Equal.trans(List<&1, Array<F32>>, T.fpar(e, hh1, TA.half(n), h, dm), fmap(h, dm, T.hcat(T.FS, hh1)), fmap(h, dm, l), f1, Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, z), T.hcat(T.FS, hh1), l, cat1)))
366      +q2 = Equal.trans(List<&1, Array<F32>>, T.fpar(e, T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), Nat.sub(n, TA.half(n)), h, dm), T.fpar(e, hh2, Nat.sub(n, TA.half(n)), h, dm), fmap(h, dm, r), Equal.cong(T.Halves<T.FS>, List<&1, Array<F32>>, z => T.fpar(e, z, Nat.sub(n, TA.half(n)), h, dm), T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), hh2, Equal.sym(T.Halves<T.FS>, hh2, T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), s2)), Equal.trans(List<&1, Array<F32>>, T.fpar(e, hh2, Nat.sub(n, TA.half(n)), h, dm), fmap(h, dm, T.hcat(T.FS, hh2)), fmap(h, dm, r), f2, Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, z), T.hcat(T.FS, hh2), r, cat2)))
367      +bb = Equal.trans(List<&1, Array<F32>>, fmap(h, dm, List.append(&1, T.FS, l, r)), fmap(h, dm, List.append(&1, T.FS, y1, y2)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, z), List.append(&1, T.FS, l, r), List.append(&1, T.FS, y1, y2), app2(T.FS, l, y1, r, y2, Equal.sym(List<&1, T.FS>, y1, l, ly1), Equal.sym(List<&1, T.FS>, y2, r, ly2))), Equal.trans(List<&1, Array<F32>>, fmap(h, dm, List.append(&1, T.FS, y1, y2)), List.append(&1, Array<F32>, fmap(h, dm, y1), fmap(h, dm, y2)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), fa, app2(Array<F32>, fmap(h, dm, y1), fmap(h, dm, l), fmap(h, dm, y2), fmap(h, dm, r), Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, z), y1, l, ly1), Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, z), y2, r, ly2))))
368      MR{List.append(&1, T.FS, y1b, y2), app2(T.FS, y1b, l, y2, r, Equal.trans(List<&1, T.FS>, y1b, y1, l, sb, ly1), ly2),
369        Equal.trans(List<&1, Array<F32>>, List.append(&1, Array<F32>, T.fpar(e, T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}), TA.half(n), h, dm), T.fpar(e, T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), Nat.sub(n, TA.half(n)), h, dm)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), fmap(h, dm, List.append(&1, T.FS, l, r)), app2(Array<F32>, T.fpar(e, T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}), TA.half(n), h, dm), fmap(h, dm, l), T.fpar(e, T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), Nat.sub(n, TA.half(n)), h, dm), fmap(h, dm, r), q1, q2), Equal.sym(List<&1, Array<F32>>, fmap(h, dm, List.append(&1, T.FS, l, r)), List.append(&1, Array<F32>, fmap(h, dm, l), fmap(h, dm, r)), bb))}
370
371def m1b(-e: Nat, -l: List<&1, T.FS>, -r: List<&1, T.FS>, +n: Nat, +h: Nat, +dm: T.Dm, -hh1: T.Halves<T.FS>, s1: {hh1 == T.cut(T.FS, TA.half(TA.half(n)), l, Nil{}) : T.Halves<T.FS>}, cat1: {T.hcat(T.FS, hh1) == l : List<&1, T.FS>}, -hh2: T.Halves<T.FS>, s2: {hh2 == T.cut(T.FS, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}) : T.Halves<T.FS>}, cat2: {T.hcat(T.FS, hh2) == r : List<&1, T.FS>}, r1: MR<e, hh1, TA.half(n), h, dm>, r2: MR<e, hh2, Nat.sub(n, TA.half(n)), h, dm>) -> MR<1n+e, T.Halves{l, r}, n, h, dm>:
372  match r1 r2:
373    case MR{y1, sy1, f1} MR{y2, sy2, f2}:
374      m1c(e, l, r, n, h, dm, hh1, s1, cat1, hh2, s2, cat2, y1, sy1, f1, y2, sy2, f2, map_app(y1, h, dm, y2))
375
376def m1a(-e: Nat, -l: List<&1, T.FS>, -r: List<&1, T.FS>, +n: Nat, +h: Nat, +dm: T.Dm, c1: CGR<TA.half(TA.half(n)), l, Nil{}>, c2: CGR<TA.half(Nat.sub(n, TA.half(n))), r, Nil{}>, k1: @g: T.Halves<T.FS> -> MR<e, g, TA.half(n), h, dm>, k2: @g: T.Halves<T.FS> -> MR<e, g, Nat.sub(n, TA.half(n)), h, dm>) -> MR<1n+e, T.Halves{l, r}, n, h, dm>:
377  match c1 c2:
378    case CGR{hh1, s1, cat1} CGR{hh2, s2, cat2}:
379      m1b(e, l, r, n, h, dm, hh1, s1, cat1, hh2, s2, cat2, k1(hh1), k2(hh2))
380
381def tree(d: Nat, gs: T.Halves<T.FS>, +n: Nat, +h: Nat, +dm: T.Dm) -> MR<d, gs, n, h, dm>:
382  match d gs:
383    case 0n T.Halves{l, r}:
384      m0a(l, r, n, h, dm, l1(l, h, dm, Nil{}))
385    case 1n++e T.Halves{l, r}:
386      m1a(e, l, r, n, h, dm, cg(TA.half(TA.half(n)), l, Nil{}), cg(TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), g1 => tree(e, g1, TA.half(n), h, dm), g2 => tree(e, g2, Nat.sub(n, TA.half(n)), h, dm))
387
388# the law: the tree gives what fleaf, the loop over the sequences one after another, gives
389def par_fin(-d: Nat, -gs: T.Halves<T.FS>, -n: Nat, +h: Nat, +dm: T.Dm, -ys: List<&1, T.FS>, +sy: {ys == T.hcat(T.FS, gs) : List<&1, T.FS>}, f: {T.fpar(d, gs, n, h, dm) == fmap(h, dm, T.hcat(T.FS, gs)) : List<&1, Array<F32>>}, r: L1R<h, dm, ys, Nil{}>) -> {T.fpar(d, gs, n, h, dm) == T.fleaf(T.hcat(T.FS, gs), h, dm, Nil{}) : List<&1, Array<F32>>}:
390  match r:
391    case L1R{ys2, s2, fl}:
392      Equal.trans(List<&1, Array<F32>>, T.fpar(d, gs, n, h, dm), fmap(h, dm, T.hcat(T.FS, gs)), T.fleaf(T.hcat(T.FS, gs), h, dm, Nil{}), f,
393        Equal.sym(List<&1, Array<F32>>, T.fleaf(T.hcat(T.FS, gs), h, dm, Nil{}), fmap(h, dm, T.hcat(T.FS, gs)),
394          Equal.trans(List<&1, Array<F32>>, T.fleaf(T.hcat(T.FS, gs), h, dm, Nil{}), T.fleaf(ys, h, dm, Nil{}), fmap(h, dm, T.hcat(T.FS, gs)), Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => T.fleaf(z, h, dm, Nil{}), T.hcat(T.FS, gs), ys, Equal.sym(List<&1, T.FS>, ys, T.hcat(T.FS, gs), sy)),
395            Equal.trans(List<&1, Array<F32>>, T.fleaf(ys, h, dm, Nil{}), fmap(h, dm, ys), fmap(h, dm, T.hcat(T.FS, gs)), fl, Equal.cong(List<&1, T.FS>, List<&1, Array<F32>>, z => fmap(h, dm, z), ys, T.hcat(T.FS, gs), sy)))))
396
397def par_mid(-d: Nat, -gs: T.Halves<T.FS>, -n: Nat, +h: Nat, +dm: T.Dm, r: MR<d, gs, n, h, dm>) -> {T.fpar(d, gs, n, h, dm) == T.fleaf(T.hcat(T.FS, gs), h, dm, Nil{}) : List<&1, Array<F32>>}:
398  match r:
399    case MR{ys, sy, f}:
400      par_fin(d, gs, n, h, dm, ys, sy, f, l1(ys, h, dm, Nil{}))
401
402# PROOF (attn_par_fwd): by induction on the depth, each fact handing its list back (the lists hold arrays, so each is
403# used once): a leaf pair is fleaf twice, and fleaf is the map pushed onto its accumulator (l1); the map of two lists
404# appended is the two maps appended (map_app); cut's halves, appended, are the list it cut (cg); a deeper tree is two
405# trees on cut's halves (the closures).
406def Laws.attn_par_fwd(d, gs, n, h, dm):
407  par_mid(d, gs, n, h, dm, tree(d, gs, n, h, dm))
408
409# ---- the sequential map the b_tree is compared with: f(x) = fs_o(fheads(h, 0, dm, x)) for each x, in order ----
410
411def b_fmap(+h: Nat, +dm: T.Dm, xs: List<&1, T.BG>) -> List<&1, T.DB>:
412  match xs:
413    case Nil{}:
414      Nil{}
415    case Con{x, t}:
416      T.db_of(T.bgroups(h, 0n, dm, x)) <> b_fmap(h, dm, t)
417
418# ---- fleaf (the code's loop with an accumulator) is the map pushed onto the accumulator ----
419
420type b_L1R<-h: Nat, -dm: T.Dm, -xs: List<&1, T.BG>, -acc: List<&1, T.DB>> is Type:
421  b_L1R{ys: List<&1, T.BG>, same: {ys == xs : List<&1, T.BG>}, fact: {T.bleaf(xs, h, dm, acc) == List.reverse.go(&1, T.DB, acc, b_fmap(h, dm, xs)) : List<&1, T.DB>}}
422
423def b_l1_con(x: T.BG, -t: List<&1, T.BG>, +h: Nat, +dm: T.Dm, -acc: List<&1, T.DB>, r: b_L1R<h, dm, t, T.db_of(T.bgroups(h, 0n, dm, x)) <> acc>) -> b_L1R<h, dm, x <> t, acc>:
424  match r:
425    case b_L1R{ys, same, fact}:
426      b_L1R{x <> ys, Equal.cong(List<&1, T.BG>, List<&1, T.BG>, z => x <> z, ys, t, same), fact}
427
428def b_l1(xs: List<&1, T.BG>, +h: Nat, +dm: T.Dm, -acc: List<&1, T.DB>) -> b_L1R<h, dm, xs, acc>:
429  match xs:
430    case Nil{}:
431      b_L1R{Nil{}, {==}, {==}}
432    case Con{x, t}:
433      b_l1_con(x, t, h, dm, acc, b_l1(t, h, dm, T.db_of(T.bgroups(h, 0n, dm, x)) <> acc))
434
435# ---- the map of two lists appended is the two maps appended ----
436
437type b_MAR<-h: Nat, -dm: T.Dm, -a: List<&1, T.BG>, -b: List<&1, T.BG>> is Type:
438  b_MAR{ys: List<&1, T.BG>, same: {ys == a : List<&1, T.BG>}, fact: {b_fmap(h, dm, List.append(&1, T.BG, a, b)) == List.append(&1, T.DB, b_fmap(h, dm, a), b_fmap(h, dm, b)) : List<&1, T.DB>}}
439
440def b_ma_con(x: T.BG, -t: List<&1, T.BG>, +h: Nat, +dm: T.Dm, -b: List<&1, T.BG>, r: b_MAR<h, dm, t, b>) -> b_MAR<h, dm, x <> t, b>:
441  match r:
442    case b_MAR{ys, same, fact}:
443      b_MAR{x <> ys, Equal.cong(List<&1, T.BG>, List<&1, T.BG>, z => x <> z, ys, t, same), Equal.cong(List<&1, T.DB>, List<&1, T.DB>, z => T.db_of(T.bgroups(h, 0n, dm, x)) <> z, b_fmap(h, dm, List.append(&1, T.BG, t, b)), List.append(&1, T.DB, b_fmap(h, dm, t), b_fmap(h, dm, b)), fact)}
444
445def b_map_app(a: List<&1, T.BG>, +h: Nat, +dm: T.Dm, -b: List<&1, T.BG>) -> b_MAR<h, dm, a, b>:
446  match a:
447    case Nil{}:
448      b_MAR{Nil{}, {==}, {==}}
449    case Con{x, t}:
450      b_ma_con(x, t, h, dm, b, b_map_app(t, h, dm, b))
451
452# ---- a reversed onto b, then c appended: a reversed onto b ++ c ----
453
454type b_GAR<-a: List<&1, T.BG>, -b: List<&1, T.BG>, -c: List<&1, T.BG>> is Type:
455  b_GAR{ys: List<&1, T.BG>, same: {ys == a : List<&1, T.BG>}, fact: {List.append(&1, T.BG, List.reverse.go(&1, T.BG, a, b), c) == List.reverse.go(&1, T.BG, a, List.append(&1, T.BG, b, c)) : List<&1, T.BG>}}
456
457def b_ga_con(x: T.BG, -t: List<&1, T.BG>, -b: List<&1, T.BG>, -c: List<&1, T.BG>, r: b_GAR<t, x <> b, c>) -> b_GAR<x <> t, b, c>:
458  match r:
459    case b_GAR{ys, same, fact}:
460      b_GAR{x <> ys, Equal.cong(List<&1, T.BG>, List<&1, T.BG>, z => x <> z, ys, t, same), fact}
461
462def b_go_app(a: List<&1, T.BG>, -b: List<&1, T.BG>, -c: List<&1, T.BG>) -> b_GAR<a, b, c>:
463  match a:
464    case Nil{}:
465      b_GAR{Nil{}, {==}, {==}}
466    case Con{x, t}:
467      b_ga_con(x, t, b, c, b_go_app(t, x <> b, c))
468
469# ---- cut gives two halves that, appended, are acc reversed onto xs ----
470
471type b_CGR<-k: Nat, -xs: List<&1, T.BG>, -acc: List<&1, T.BG>> is Type:
472  b_CGR{hh: T.Halves<T.BG>, same: {hh == T.cut(T.BG, k, xs, acc) : T.Halves<T.BG>}, cat: {T.hcat(T.BG, hh) == List.reverse.go(&1, T.BG, acc, xs) : List<&1, T.BG>}}
473
474def b_cg_base(-k: Nat, xs: List<&1, T.BG>, -acc: List<&1, T.BG>, e: {T.cut(T.BG, k, xs, acc) == T.Halves{List.reverse(&1, T.BG, acc), xs} : T.Halves<T.BG>}, r: b_GAR<acc, Nil{}, xs>) -> b_CGR<k, xs, acc>:
475  match r:
476    case b_GAR{ys, +same, fact}:
477      b_CGR{T.Halves{List.reverse(&1, T.BG, ys), xs},
478        Equal.trans(T.Halves<T.BG>, T.Halves{List.reverse(&1, T.BG, ys), xs}, T.Halves{List.reverse(&1, T.BG, acc), xs}, T.cut(T.BG, k, xs, acc), Equal.cong(List<&1, T.BG>, T.Halves<T.BG>, z => T.Halves{List.reverse(&1, T.BG, z), xs}, ys, acc, same), Equal.sym(T.Halves<T.BG>, T.cut(T.BG, k, xs, acc), T.Halves{List.reverse(&1, T.BG, acc), xs}, e)),
479        Equal.trans(List<&1, T.BG>, List.append(&1, T.BG, List.reverse.go(&1, T.BG, ys, Nil{}), xs), List.append(&1, T.BG, List.reverse.go(&1, T.BG, acc, Nil{}), xs), List.reverse.go(&1, T.BG, acc, xs), Equal.cong(List<&1, T.BG>, List<&1, T.BG>, z => List.append(&1, T.BG, List.reverse.go(&1, T.BG, z, Nil{}), xs), ys, acc, same), fact)}
480
481def b_cg_con(-m: Nat, -x: T.BG, -t: List<&1, T.BG>, -acc: List<&1, T.BG>, r: b_CGR<m, t, x <> acc>) -> b_CGR<1n+m, x <> t, acc>:
482  match r:
483    case b_CGR{hh, same, cat}:
484      b_CGR{hh, same, cat}
485
486def b_cg(k: Nat, xs: List<&1, T.BG>, acc: List<&1, T.BG>) -> b_CGR<k, xs, acc>:
487  match k xs:
488    case 1n+m Con{x, t}:
489      b_cg_con(m, x, t, acc, b_cg(m, t, x <> acc))
490    case 0n ys:
491      b_cg_base(0n, ys, acc, {==}, b_go_app(acc, Nil{}, ys))
492    case 1n+m Nil{}:
493      b_cg_base(1n+m, Nil{}, acc, {==}, b_go_app(acc, Nil{}, Nil{}))
494
495# ---- the b_tree: fpar at depth d on two halves is the map of the halves appended ----
496
497type b_MR<-d: Nat, -gs: T.Halves<T.BG>, -n: Nat, -h: Nat, -dm: T.Dm> is Type:
498  b_MR{ys: List<&1, T.BG>, same: {ys == T.hcat(T.BG, gs) : List<&1, T.BG>}, fact: {T.bpar(d, gs, n, h, dm) == b_fmap(h, dm, T.hcat(T.BG, gs)) : List<&1, T.DB>}}
499
500# depth 0: the two leaves' loops, appended
501def b_m0c(-l: List<&1, T.BG>, -r: List<&1, T.BG>, -n: Nat, +h: Nat, +dm: T.Dm, -l1y: List<&1, T.BG>, +sl: {l1y == l : List<&1, T.BG>}, fl: {T.bleaf(l, h, dm, Nil{}) == b_fmap(h, dm, l) : List<&1, T.DB>}, r1: List<&1, T.BG>, sr: {r1 == r : List<&1, T.BG>}, fr: {T.bleaf(r, h, dm, Nil{}) == b_fmap(h, dm, r) : List<&1, T.DB>}, c: b_MAR<h, dm, l1y, r>) -> b_MR<0n, T.Halves{l, r}, n, h, dm>:
502  match c:
503    case b_MAR{l2, s2, fa}:
504      b_MR{List.append(&1, T.BG, l2, r1), app2(T.BG, l2, l, r1, r, Equal.trans(List<&1, T.BG>, l2, l1y, l, s2, sl), sr),
505        Equal.trans(List<&1, T.DB>, List.append(&1, T.DB, T.bleaf(l, h, dm, Nil{}), T.bleaf(r, h, dm, Nil{})), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), b_fmap(h, dm, List.append(&1, T.BG, l, r)), app2(T.DB, T.bleaf(l, h, dm, Nil{}), b_fmap(h, dm, l), T.bleaf(r, h, dm, Nil{}), b_fmap(h, dm, r), fl, fr),
506          Equal.sym(List<&1, T.DB>, b_fmap(h, dm, List.append(&1, T.BG, l, r)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)),
507            Equal.trans(List<&1, T.DB>, b_fmap(h, dm, List.append(&1, T.BG, l, r)), b_fmap(h, dm, List.append(&1, T.BG, l1y, r)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, List.append(&1, T.BG, z, r)), l, l1y, Equal.sym(List<&1, T.BG>, l1y, l, sl)),
508              Equal.trans(List<&1, T.DB>, b_fmap(h, dm, List.append(&1, T.BG, l1y, r)), List.append(&1, T.DB, b_fmap(h, dm, l1y), b_fmap(h, dm, r)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), fa, Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => List.append(&1, T.DB, b_fmap(h, dm, z), b_fmap(h, dm, r)), l1y, l, sl)))))}
509
510def b_m0b(-l: List<&1, T.BG>, -r: List<&1, T.BG>, -n: Nat, +h: Nat, +dm: T.Dm, l1y: List<&1, T.BG>, +sl: {l1y == l : List<&1, T.BG>}, fl: {T.bleaf(l, h, dm, Nil{}) == b_fmap(h, dm, l) : List<&1, T.DB>}, b: b_L1R<h, dm, r, Nil{}>) -> b_MR<0n, T.Halves{l, r}, n, h, dm>:
511  match b:
512    case b_L1R{r1, sr, fr}:
513      b_m0c(l, r, n, h, dm, l1y, sl, fl, r1, sr, fr, b_map_app(l1y, h, dm, r))
514
515def b_m0a(-l: List<&1, T.BG>, r: List<&1, T.BG>, -n: Nat, +h: Nat, +dm: T.Dm, a: b_L1R<h, dm, l, Nil{}>) -> b_MR<0n, T.Halves{l, r}, n, h, dm>:
516  match a:
517    case b_L1R{l1y, sl, fl}:
518      b_m0b(l, r, n, h, dm, l1y, sl, fl, b_l1(r, h, dm, Nil{}))
519
520# depth 1 + e: each half cut in two and its b_tree (the closures run main at depth e), then the two maps appended
521def b_m1c(-e: Nat, -l: List<&1, T.BG>, -r: List<&1, T.BG>, +n: Nat, +h: Nat, +dm: T.Dm, -hh1: T.Halves<T.BG>, s1: {hh1 == T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}) : T.Halves<T.BG>}, +cat1: {T.hcat(T.BG, hh1) == l : List<&1, T.BG>}, -hh2: T.Halves<T.BG>, s2: {hh2 == T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}) : T.Halves<T.BG>}, +cat2: {T.hcat(T.BG, hh2) == r : List<&1, T.BG>}, -y1: List<&1, T.BG>, sy1: {y1 == T.hcat(T.BG, hh1) : List<&1, T.BG>}, f1: {T.bpar(e, hh1, TA.half(n), h, dm) == b_fmap(h, dm, T.hcat(T.BG, hh1)) : List<&1, T.DB>}, y2: List<&1, T.BG>, sy2: {y2 == T.hcat(T.BG, hh2) : List<&1, T.BG>}, f2: {T.bpar(e, hh2, Nat.sub(n, TA.half(n)), h, dm) == b_fmap(h, dm, T.hcat(T.BG, hh2)) : List<&1, T.DB>}, ma: b_MAR<h, dm, y1, y2>) -> b_MR<1n+e, T.Halves{l, r}, n, h, dm>:
522  match ma:
523    case b_MAR{y1b, sb, fa}:
524      +ly1 = Equal.trans(List<&1, T.BG>, y1, T.hcat(T.BG, hh1), l, sy1, cat1)
525      +ly2 = Equal.trans(List<&1, T.BG>, y2, T.hcat(T.BG, hh2), r, sy2, cat2)
526      +q1 = Equal.trans(List<&1, T.DB>, T.bpar(e, T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}), TA.half(n), h, dm), T.bpar(e, hh1, TA.half(n), h, dm), b_fmap(h, dm, l), Equal.cong(T.Halves<T.BG>, List<&1, T.DB>, z => T.bpar(e, z, TA.half(n), h, dm), T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}), hh1, Equal.sym(T.Halves<T.BG>, hh1, T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}), s1)), Equal.trans(List<&1, T.DB>, T.bpar(e, hh1, TA.half(n), h, dm), b_fmap(h, dm, T.hcat(T.BG, hh1)), b_fmap(h, dm, l), f1, Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, z), T.hcat(T.BG, hh1), l, cat1)))
527      +q2 = Equal.trans(List<&1, T.DB>, T.bpar(e, T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), Nat.sub(n, TA.half(n)), h, dm), T.bpar(e, hh2, Nat.sub(n, TA.half(n)), h, dm), b_fmap(h, dm, r), Equal.cong(T.Halves<T.BG>, List<&1, T.DB>, z => T.bpar(e, z, Nat.sub(n, TA.half(n)), h, dm), T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), hh2, Equal.sym(T.Halves<T.BG>, hh2, T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), s2)), Equal.trans(List<&1, T.DB>, T.bpar(e, hh2, Nat.sub(n, TA.half(n)), h, dm), b_fmap(h, dm, T.hcat(T.BG, hh2)), b_fmap(h, dm, r), f2, Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, z), T.hcat(T.BG, hh2), r, cat2)))
528      +bb = Equal.trans(List<&1, T.DB>, b_fmap(h, dm, List.append(&1, T.BG, l, r)), b_fmap(h, dm, List.append(&1, T.BG, y1, y2)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, z), List.append(&1, T.BG, l, r), List.append(&1, T.BG, y1, y2), app2(T.BG, l, y1, r, y2, Equal.sym(List<&1, T.BG>, y1, l, ly1), Equal.sym(List<&1, T.BG>, y2, r, ly2))), Equal.trans(List<&1, T.DB>, b_fmap(h, dm, List.append(&1, T.BG, y1, y2)), List.append(&1, T.DB, b_fmap(h, dm, y1), b_fmap(h, dm, y2)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), fa, app2(T.DB, b_fmap(h, dm, y1), b_fmap(h, dm, l), b_fmap(h, dm, y2), b_fmap(h, dm, r), Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, z), y1, l, ly1), Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, z), y2, r, ly2))))
529      b_MR{List.append(&1, T.BG, y1b, y2), app2(T.BG, y1b, l, y2, r, Equal.trans(List<&1, T.BG>, y1b, y1, l, sb, ly1), ly2),
530        Equal.trans(List<&1, T.DB>, List.append(&1, T.DB, T.bpar(e, T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}), TA.half(n), h, dm), T.bpar(e, T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), Nat.sub(n, TA.half(n)), h, dm)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), b_fmap(h, dm, List.append(&1, T.BG, l, r)), app2(T.DB, T.bpar(e, T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}), TA.half(n), h, dm), b_fmap(h, dm, l), T.bpar(e, T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), Nat.sub(n, TA.half(n)), h, dm), b_fmap(h, dm, r), q1, q2), Equal.sym(List<&1, T.DB>, b_fmap(h, dm, List.append(&1, T.BG, l, r)), List.append(&1, T.DB, b_fmap(h, dm, l), b_fmap(h, dm, r)), bb))}
531
532def b_m1b(-e: Nat, -l: List<&1, T.BG>, -r: List<&1, T.BG>, +n: Nat, +h: Nat, +dm: T.Dm, -hh1: T.Halves<T.BG>, s1: {hh1 == T.cut(T.BG, TA.half(TA.half(n)), l, Nil{}) : T.Halves<T.BG>}, cat1: {T.hcat(T.BG, hh1) == l : List<&1, T.BG>}, -hh2: T.Halves<T.BG>, s2: {hh2 == T.cut(T.BG, TA.half(Nat.sub(n, TA.half(n))), r, Nil{}) : T.Halves<T.BG>}, cat2: {T.hcat(T.BG, hh2) == r : List<&1, T.BG>}, r1: b_MR<e, hh1, TA.half(n), h, dm>, r2: b_MR<e, hh2, Nat.sub(n, TA.half(n)), h, dm>) -> b_MR<1n+e, T.Halves{l, r}, n, h, dm>:
533  match r1 r2:
534    case b_MR{y1, sy1, f1} b_MR{y2, sy2, f2}:
535      b_m1c(e, l, r, n, h, dm, hh1, s1, cat1, hh2, s2, cat2, y1, sy1, f1, y2, sy2, f2, b_map_app(y1, h, dm, y2))
536
537def b_m1a(-e: Nat, -l: List<&1, T.BG>, -r: List<&1, T.BG>, +n: Nat, +h: Nat, +dm: T.Dm, c1: b_CGR<TA.half(TA.half(n)), l, Nil{}>, c2: b_CGR<TA.half(Nat.sub(n, TA.half(n))), r, Nil{}>, k1: @g: T.Halves<T.BG> -> b_MR<e, g, TA.half(n), h, dm>, k2: @g: T.Halves<T.BG> -> b_MR<e, g, Nat.sub(n, TA.half(n)), h, dm>) -> b_MR<1n+e, T.Halves{l, r}, n, h, dm>:
538  match c1 c2:
539    case b_CGR{hh1, s1, cat1} b_CGR{hh2, s2, cat2}:
540      b_m1b(e, l, r, n, h, dm, hh1, s1, cat1, hh2, s2, cat2, k1(hh1), k2(hh2))
541
542def b_tree(d: Nat, gs: T.Halves<T.BG>, +n: Nat, +h: Nat, +dm: T.Dm) -> b_MR<d, gs, n, h, dm>:
543  match d gs:
544    case 0n T.Halves{l, r}:
545      b_m0a(l, r, n, h, dm, b_l1(l, h, dm, Nil{}))
546    case 1n++e T.Halves{l, r}:
547      b_m1a(e, l, r, n, h, dm, b_cg(TA.half(TA.half(n)), l, Nil{}), b_cg(TA.half(Nat.sub(n, TA.half(n))), r, Nil{}), g1 => b_tree(e, g1, TA.half(n), h, dm), g2 => b_tree(e, g2, Nat.sub(n, TA.half(n)), h, dm))
548
549# the law: the b_tree gives what fleaf, the loop over the sequences one after another, gives
550def b_par_fin(-d: Nat, -gs: T.Halves<T.BG>, -n: Nat, +h: Nat, +dm: T.Dm, -ys: List<&1, T.BG>, +sy: {ys == T.hcat(T.BG, gs) : List<&1, T.BG>}, f: {T.bpar(d, gs, n, h, dm) == b_fmap(h, dm, T.hcat(T.BG, gs)) : List<&1, T.DB>}, r: b_L1R<h, dm, ys, Nil{}>) -> {T.bpar(d, gs, n, h, dm) == T.bleaf(T.hcat(T.BG, gs), h, dm, Nil{}) : List<&1, T.DB>}:
551  match r:
552    case b_L1R{ys2, s2, fl}:
553      Equal.trans(List<&1, T.DB>, T.bpar(d, gs, n, h, dm), b_fmap(h, dm, T.hcat(T.BG, gs)), T.bleaf(T.hcat(T.BG, gs), h, dm, Nil{}), f,
554        Equal.sym(List<&1, T.DB>, T.bleaf(T.hcat(T.BG, gs), h, dm, Nil{}), b_fmap(h, dm, T.hcat(T.BG, gs)),
555          Equal.trans(List<&1, T.DB>, T.bleaf(T.hcat(T.BG, gs), h, dm, Nil{}), T.bleaf(ys, h, dm, Nil{}), b_fmap(h, dm, T.hcat(T.BG, gs)), Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => T.bleaf(z, h, dm, Nil{}), T.hcat(T.BG, gs), ys, Equal.sym(List<&1, T.BG>, ys, T.hcat(T.BG, gs), sy)),
556            Equal.trans(List<&1, T.DB>, T.bleaf(ys, h, dm, Nil{}), b_fmap(h, dm, ys), b_fmap(h, dm, T.hcat(T.BG, gs)), fl, Equal.cong(List<&1, T.BG>, List<&1, T.DB>, z => b_fmap(h, dm, z), ys, T.hcat(T.BG, gs), sy)))))
557
558def b_par_mid(-d: Nat, -gs: T.Halves<T.BG>, -n: Nat, +h: Nat, +dm: T.Dm, r: b_MR<d, gs, n, h, dm>) -> {T.bpar(d, gs, n, h, dm) == T.bleaf(T.hcat(T.BG, gs), h, dm, Nil{}) : List<&1, T.DB>}:
559  match r:
560    case b_MR{ys, sy, f}:
561      b_par_fin(d, gs, n, h, dm, ys, sy, f, b_l1(ys, h, dm, Nil{}))
562
563# PROOF (attn_par_bwd): attn_par_fwd's proof, for BG and bleaf.
564def Laws.attn_par_bwd(d, gs, n, h, dm):
565  b_par_mid(d, gs, n, h, dm, b_tree(d, gs, n, h, dm))
566
567# =====================================================================================================
568# Grouped-query heads (llama.bend's proof)
569# =====================================================================================================
570
571# one block of 1 + m numbers adds 1 to the quotient (Nat.divmod.go counts down the remainder from m)
572def div_block(+m: Nat, -n: Nat, -d: Nat, -r: Nat) -> {Nat.divmod.go(Nat.add(1n+m, n), m, d, r) == Nat.divmod.go(n, Nat.add(m, r), 1n+d, 0n) : Nat & Nat}:
573  match m:
574    case 0n:
575      {==}
576    case 1n+p:
577      %Equal.sym(Nat, 1n+Nat.add(p, r), Nat.add(p, 1n+r), NL.add_succ(p, r)) : {Nat.divmod.go(Nat.add(1n+p, n), p, d, 1n+r) == Nat.divmod.go(n, _, 1n+d, 0n) : Nat & Nat}
578      div_block(p, n, d, 1n+r)
579
580# j whole blocks of 1 + s numbers add j to the quotient
581def div_blocks(+j: Nat, +s: Nat, +n: Nat, +d: Nat) -> {Nat.divmod.go(Nat.add(Nat.mul(j, 1n+s), n), s, d, 0n) == Nat.divmod.go(n, s, Nat.add(j, d), 0n) : Nat & Nat}:
582  match j:
583    case 0n:
584      {==}
585    case 1n+jp:
586      %NL.add_assoc(1n+s, Nat.mul(jp, 1n+s), n) : {Nat.divmod.go(_, s, d, 0n) == Nat.divmod.go(n, s, Nat.add(1n+jp, d), 0n) : Nat & Nat}
587      %Equal.sym(Nat & Nat, Nat.divmod.go(Nat.add(1n+s, Nat.add(Nat.mul(jp, 1n+s), n)), s, d, 0n), Nat.divmod.go(Nat.add(Nat.mul(jp, 1n+s), n), Nat.add(s, 0n), 1n+d, 0n), div_block(s, Nat.add(Nat.mul(jp, 1n+s), n), d, 0n)) : {_ == Nat.divmod.go(n, s, Nat.add(1n+jp, d), 0n) : Nat & Nat}
588      %Equal.sym(Nat, Nat.add(s, 0n), s, NL.add_zero(s)) : {Nat.divmod.go(Nat.add(Nat.mul(jp, 1n+s), n), _, 1n+d, 0n) == Nat.divmod.go(n, s, Nat.add(1n+jp, d), 0n) : Nat & Nat}
589      %Equal.sym(Nat, 1n+Nat.add(jp, d), Nat.add(jp, 1n+d), NL.add_succ(jp, d)) : {Nat.divmod.go(Nat.add(Nat.mul(jp, 1n+s), n), s, 1n+d, 0n) == Nat.divmod.go(n, s, _, 0n) : Nat & Nat}
590      div_blocks(jp, s, n, 1n+d)
591
592# fewer than 1 + s numbers after the last whole block leave the quotient alone
593def div_rest(+i: Nat, -k: Nat, -d: Nat, -r: Nat) -> {Pair.fst(Nat, Nat, Nat.divmod.go(i, Nat.add(i, k), d, r)) == d : Nat}:
594  match i:
595    case 0n:
596      {==}
597    case 1n+p:
598      div_rest(p, k, d, 1n+r)
599
600# PROOF (gqa_head): Nat.div counts how many whole blocks of g numbers fit. j·g is j whole blocks (div_blocks), and
601# i < g numbers after them do not complete another one (div_rest).
602def Laws.gqa_head(j, i, k):
603  %Equal.sym(Nat & Nat, Nat.divmod.go(Nat.add(Nat.mul(j, 1n+Nat.add(i, k)), i), Nat.add(i, k), 0n, 0n), Nat.divmod.go(i, Nat.add(i, k), Nat.add(j, 0n), 0n), div_blocks(j, Nat.add(i, k), i, 0n)) : {Pair.fst(Nat, Nat, _) == j : Nat}
604  %NL.add_zero(j) : {Pair.fst(Nat, Nat, Nat.divmod.go(i, Nat.add(i, k), Nat.add(j, 0n), 0n)) == _ : Nat}
605  div_rest(i, k, Nat.add(j, 0n), 0n)
606
607# PROOF (kv_of_group): kv_of is Nat.div, so this is gqa_head.
608def Laws.kv_of_group(j, i, k):
609  Laws.gqa_head(j, i, k)
610
611# PROOF (kv_cols): head_cols' key column is kv_of(head, g)·hd; kv_of of a head of group j is j (kv_of_group).
612def Laws.kv_cols(t, hd, w, kvw, sc, j, i, k):
613  Equal.cong(Nat, U32, n => U32.from_nat(Nat.mul(n, hd)), T.kv_of(Nat.add(Nat.mul(j, 1n+Nat.add(i, k)), i), 1n+Nat.add(i, k)), j, Laws.kv_of_group(j, i, k))
614
615# =====================================================================================================
616# Tensors: shapes
617# =====================================================================================================
618
619# a || b == b || a, and a && b == b && a: every case computes
620def or_comm(+a: Bool, +b: Bool) -> {Bool.or(a, b) == Bool.or(b, a) : Bool}:
621  match a b:
622    case True{} True{}:
623      {==}
624    case True{} False{}:
625      {==}
626    case False{} True{}:
627      {==}
628    case False{} False{}:
629      {==}
630
631def and_comm(+a: Bool, +b: Bool) -> {Bool.and(a, b) == Bool.and(b, a) : Bool}:
632  match a b:
633    case True{} True{}:
634      {==}
635    case True{} False{}:
636      {==}
637    case False{} True{}:
638      {==}
639    case False{} False{}:
640      {==}
641
642# equal operands give equal conjunctions and disjunctions
643def and_cong(+p: Bool, +p2: Bool, +q: Bool, +q2: Bool, e: {p == p2 : Bool}, f: {q == q2 : Bool}) -> {Bool.and(p, q) == Bool.and(p2, q2) : Bool}:
644  Equal.trans(Bool, Bool.and(p, q), Bool.and(p2, q), Bool.and(p2, q2), Equal.cong(Bool, Bool, x => Bool.and(x, q), p, p2, e), Equal.cong(Bool, Bool, x => Bool.and(p2, x), q, q2, f))
645
646def or_cong(+p: Bool, +p2: Bool, +q: Bool, +q2: Bool, e: {p == p2 : Bool}, f: {q == q2 : Bool}) -> {Bool.or(p, q) == Bool.or(p2, q2) : Bool}:
647  Equal.trans(Bool, Bool.or(p, q), Bool.or(p2, q), Bool.or(p2, q2), Equal.cong(Bool, Bool, x => Bool.or(x, q), p, p2, e), Equal.cong(Bool, Bool, x => Bool.or(p2, x), q, q2, f))
648
649# one axis: bc_dim is written as pair(x, y) || pair(y, x), so swapping x and y only swaps the two sides of the ||
650def bc_dim_sym(+x: Nat, +y: Nat, +z: Nat) -> {TT.bc_dim(x, y, z) == TT.bc_dim(y, x, z) : Bool}:
651  or_comm(TT.bc_pair(x, y, z), TT.bc_pair(y, x, z))
652
653# axis by axis: the same on each axis (bc_dim_sym), and by induction on the rest; shapes of different ranks are False
654# either way round
655def bc_eq_sym(a: List<&2, Nat>, b: List<&2, Nat>, o: List<&2, Nat>) -> {TT.bc_eq(a, b, o) == TT.bc_eq(b, a, o) : Bool}:
656  match a b o:
657    case Nil{} Nil{} Nil{}:
658      {==}
659    case Nil{} Nil{} Con{z, ro}:
660      {==}
661    case Nil{} Con{y, rb} Nil{}:
662      {==}
663    case Nil{} Con{y, rb} Con{z, ro}:
664      {==}
665    case Con{x, ra} Nil{} Nil{}:
666      {==}
667    case Con{x, ra} Nil{} Con{z, ro}:
668      {==}
669    case Con{x, ra} Con{y, rb} Nil{}:
670      {==}
671    case Con{+x, +ra} Con{+y, +rb} Con{+z, +ro}:
672      and_cong(TT.bc_dim(x, y, z), TT.bc_dim(y, x, z), TT.bc_eq(ra, rb, ro), TT.bc_eq(rb, ra, ro), bc_dim_sym(x, y, z), bc_eq_sym(ra, rb, ro))
673
674# the ranks: the same two comparisons and the same two equalities, in the other order
675def bc_rank_sym(+la: Nat, +lb: Nat, +lo: Nat) -> {TT.bc_rank(la, lb, lo) == TT.bc_rank(lb, la, lo) : Bool}:
676  and_cong(Bool.and(Nat.is_le(la, lo), Nat.is_le(lb, lo)), Bool.and(Nat.is_le(lb, lo), Nat.is_le(la, lo)), Bool.or(Nat.is_eq(la, lo), Nat.is_eq(lb, lo)), Bool.or(Nat.is_eq(lb, lo), Nat.is_eq(la, lo)),
677    and_comm(Nat.is_le(la, lo), Nat.is_le(lb, lo)), or_comm(Nat.is_eq(la, lo), Nat.is_eq(lb, lo)))
678
679def Laws.bc_sym(a, b, o):
680  and_cong(TT.bc_rank(List.length(&2, Nat, a), List.length(&2, Nat, b), List.length(&2, Nat, o)), TT.bc_rank(List.length(&2, Nat, b), List.length(&2, Nat, a), List.length(&2, Nat, o)),
681    TT.bc_eq(TT.pad(a, List.length(&2, Nat, o)), TT.pad(b, List.length(&2, Nat, o)), o), TT.bc_eq(TT.pad(b, List.length(&2, Nat, o)), TT.pad(a, List.length(&2, Nat, o)), o),
682    bc_rank_sym(List.length(&2, Nat, a), List.length(&2, Nat, b), List.length(&2, Nat, o)), bc_eq_sym(TT.pad(a, List.length(&2, Nat, o)), TT.pad(b, List.length(&2, Nat, o)), o))
683
684# h * (a * r) == a * (h * r): associativity, then commutativity of the first two factors, then associativity back
685def mul_swap(+h: Nat, +a: Nat, +r: Nat) -> {Nat.mul(h, Nat.mul(a, r)) == Nat.mul(a, Nat.mul(h, r)) : Nat}:
686  Equal.trans(Nat, Nat.mul(h, Nat.mul(a, r)), Nat.mul(Nat.mul(h, a), r), Nat.mul(a, Nat.mul(h, r)), NL.mul_assoc(h, a, r),
687    Equal.trans(Nat, Nat.mul(Nat.mul(h, a), r), Nat.mul(Nat.mul(a, h), r), Nat.mul(a, Nat.mul(h, r)),
688      Equal.cong(Nat, Nat, x => Nat.mul(x, r), Nat.mul(h, a), Nat.mul(a, h), NL.mul_comm(h, a)),
689      Equal.sym(Nat, Nat.mul(a, Nat.mul(h, r)), Nat.mul(Nat.mul(a, h), r), NL.mul_assoc(a, h, r))))
690
691# by induction on the shape and the axis: axis 0 computes; past it, the first size h stays in front on both sides, and
692# mul_swap moves it past size(k)
693def Laws.sum_numel(s, k):
694  match s k:
695    case Nil{} _:
696      {==}
697    case Con{h, t} 0n:
698      {==}
699    case Con{+h, +t} 1n+p:
700      Equal.trans(Nat, Nat.mul(h, NL.product(t)), Nat.mul(h, Nat.mul(TT.at1(t, p), NL.product(TT.remove(t, p)))), Nat.mul(TT.at1(t, p), Nat.mul(h, NL.product(TT.remove(t, p)))),
701        Equal.cong(Nat, Nat, x => Nat.mul(h, x), NL.product(t), Nat.mul(TT.at1(t, p), NL.product(TT.remove(t, p))), Laws.sum_numel(t, p)),
702        mul_swap(h, TT.at1(t, p), NL.product(TT.remove(t, p))))
703
704# =====================================================================================================
705# Tensors: narrow, cat, of_mat, permute
706# =====================================================================================================
707
708# by induction: axis 0 is replaced and then taken out; past it, the first size stays in front on both sides
709def Laws.narrow_rest(s, d, l):
710  match s d:
711    case Nil{} _:
712      {==}
713    case Con{h, t} 0n:
714      {==}
715    case Con{+h, +t} 1n+p:
716      Equal.cong(List<&2, Nat>, List<&2, Nat>, x => h <> x, TT.remove(TT.setd(t, p, l), p), TT.remove(t, p), Laws.narrow_rest(t, p, l))
717
718# a shape with no axis d contradicts the premise (d < rank is False); axis 0 is l; past it, the induction
719def Laws.narrow_axis(s, d, l, e):
720  match s d:
721    case Nil{} 0n:
722      Empty.absurd({TT.at1(TT.setd([], 0n, l), 0n) == l : Nat}, false_true(Equal.sym(Bool, True{}, False{}, e)))
723    case Nil{} 1n+p:
724      Empty.absurd({TT.at1(TT.setd([], 1n+p, l), 1n+p) == l : Nat}, false_true(Equal.sym(Bool, True{}, False{}, e)))
725    case Con{h, t} 0n:
726      {==}
727    case Con{h, +t} 1n+p:
728      Laws.narrow_axis(t, p, l, e)
729
730# axis 0: (x + y)·n == x·n + y·n (distributivity); past it, the induction and k·(a + b) == k·a + k·b
731def Laws.cat_numel(s, d, x, y, e):
732  match s d:
733    case Nil{} 0n:
734      Empty.absurd({TT.numel(TT.setd([], 0n, Nat.add(x, y))) == Nat.add(TT.numel(TT.setd([], 0n, x)), TT.numel(TT.setd([], 0n, y))) : Nat}, false_true(Equal.sym(Bool, True{}, False{}, e)))
735    case Nil{} 1n+p:
736      Empty.absurd({TT.numel(TT.setd([], 1n+p, Nat.add(x, y))) == Nat.add(TT.numel(TT.setd([], 1n+p, x)), TT.numel(TT.setd([], 1n+p, y))) : Nat}, false_true(Equal.sym(Bool, True{}, False{}, e)))
737    case Con{h, +t} 0n:
738      Equal.sym(Nat, Nat.add(Nat.mul(x, NL.product(t)), Nat.mul(y, NL.product(t))), Nat.mul(Nat.add(x, y), NL.product(t)), NL.mul_dist(x, y, NL.product(t)))
739    case Con{+h, +t} 1n+p:
740      Equal.trans(Nat, Nat.mul(h, NL.product(TT.setd(t, p, Nat.add(x, y)))), Nat.mul(h, Nat.add(NL.product(TT.setd(t, p, x)), NL.product(TT.setd(t, p, y)))), Nat.add(Nat.mul(h, NL.product(TT.setd(t, p, x))), Nat.mul(h, NL.product(TT.setd(t, p, y)))),
741        Equal.cong(Nat, Nat, v => Nat.mul(h, v), NL.product(TT.setd(t, p, Nat.add(x, y))), Nat.add(NL.product(TT.setd(t, p, x)), NL.product(TT.setd(t, p, y))), Laws.cat_numel(t, p, x, y, e)),
742        NL.mul_dist_l(h, NL.product(TT.setd(t, p, x)), NL.product(TT.setd(t, p, y))))
743
744# r·(c·1) == r·c: c·1 == c
745def Laws.mat_numel(r, c):
746  Equal.cong(Nat, Nat, v => Nat.mul(r, v), Nat.mul(c, 1n), c, NL.mul_one_r(c))
747
748# one axis of the result per entry of p
749def Laws.permute_rank(s, p):
750  match p:
751    case Nil{}:
752      {==}
753    case Con{k, r}:
754      Equal.cong(Nat, Nat, v => 1n+v, TT.rank(TT.permuted(s, r)), List.length(&2, Nat, r), Laws.permute_rank(s, r))
755
756# =====================================================================================================
757# The order of a row's additions (block_sum)
758# =====================================================================================================
759
760# one pass over 2k blocks of 2^p cells gives the k blocks of 2^(p+1) cells: the pass adds blocks 2j and 2j+1, the two
761# halves bal puts under one node. Induction on k; add_succ turns k + (k + 1) into 2 + (k + k), and add_assoc moves the
762# next pair's start from (lo + 2^p) + 2^p to lo + 2^(p+1)
763def pass_pair(+p: Nat, +k: Nat, +lo: Nat) -> {Spec.spass(Spec.blocks(p, Nat.add(k, k), lo)) == Spec.blocks(1n+p, k, lo) : List<&2, Spec.Sum>}:
764  match k:
765    case 0n:
766      {==}
767    case 1n+j:
768      +a = Spec.pw(p)
769      +nx = Nat.add(Nat.add(lo, a), a)
770      %NL.add_succ(j, j) : {Spec.spass(Spec.blocks(p, 1n+_, lo)) == Spec.blocks(1n+p, 1n+j, lo) : List<&2, Spec.Sum>}
771      %Equal.sym(Nat, Nat.add(lo, Nat.add(a, a)), nx, NL.add_assoc(lo, a, a)) : {Spec.spass(Spec.blocks(p, 1n+1n+Nat.add(j, j), lo)) == Spec.SAdd{Spec.bal(p, lo), Spec.bal(p, Nat.add(lo, a))} <> Spec.blocks(1n+p, j, _) : List<&2, Spec.Sum>}
772      %pass_pair(p, j, nx) : {Spec.spass(Spec.blocks(p, 1n+1n+Nat.add(j, j), lo)) == Spec.SAdd{Spec.bal(p, lo), Spec.bal(p, Nat.add(lo, a))} <> _ : List<&2, Spec.Sum>}
773      {==}
774
775# 2^(p+1) · k cells are 2^p · 2k: (a + a)·k == a·k + a·k == a·(k + k)
776def cnt2(+p: Nat, +k: Nat) -> {Nat.mul(Spec.pw(1n+p), k) == Nat.mul(Spec.pw(p), Nat.add(k, k)) : Nat}:
777  +a = Spec.pw(p)
778  Equal.trans(Nat, Nat.mul(Nat.add(a, a), k), Nat.add(Nat.mul(a, k), Nat.mul(a, k)), Nat.mul(a, Nat.add(k, k)),
779    Equal.sym(Nat, Nat.add(Nat.mul(a, k), Nat.mul(a, k)), Nat.mul(Nat.add(a, a), k), NL.mul_dist(a, a, k)),
780    Equal.sym(Nat, Nat.mul(a, Nat.add(k, k)), Nat.add(Nat.mul(a, k), Nat.mul(a, k)), NL.mul_dist_l(a, k, k)))
781
782# the first p passes over a row of 2^p · k cells leave its k blocks, each summed as bal sums it. Induction on p: p
783# passes over 2^(p+1)·k cells (= 2^p·2k, cnt2) leave 2k blocks of 2^p, and one more pass pairs them (pass_pair)
784def blocks_passes(+p: Nat, +k: Nat, +lo: Nat) -> {Spec.passes(p, Spec.blocks(0n, Nat.mul(Spec.pw(p), k), lo)) == Spec.blocks(p, k, lo) : List<&2, Spec.Sum>}:
785  match p:
786    case 0n:
787      %NL.mul_one_l(k) : {Spec.blocks(0n, Nat.mul(1n, k), lo) == Spec.blocks(0n, _, lo) : List<&2, Spec.Sum>}
788      {==}
789    case 1n+q:
790      +kk = Nat.add(k, k)
791      %Equal.sym(Nat, Nat.mul(Spec.pw(1n+q), k), Nat.mul(Spec.pw(q), kk), cnt2(q, k)) : {Spec.spass(Spec.passes(q, Spec.blocks(0n, _, lo))) == Spec.blocks(1n+q, k, lo) : List<&2, Spec.Sum>}
792      %Equal.sym(List<&2, Spec.Sum>, Spec.passes(q, Spec.blocks(0n, Nat.mul(Spec.pw(q), kk), lo)), Spec.blocks(q, kk, lo), blocks_passes(q, kk, lo)) : {Spec.spass(_) == Spec.blocks(1n+q, k, lo) : List<&2, Spec.Sum>}
793      pass_pair(q, k, lo)
794
795# r + p passes are p passes, then r more
796def passes_add(r: Nat, +p: Nat, +xs: List<&2, Spec.Sum>) -> {Spec.passes(Nat.add(r, p), xs) == Spec.passes(r, Spec.passes(p, xs)) : List<&2, Spec.Sum>}:
797  match r:
798    case 0n:
799      {==}
800    case 1n+q:
801      Equal.cong(List<&2, Spec.Sum>, List<&2, Spec.Sum>, z => Spec.spass(z), Spec.passes(Nat.add(q, p), xs), Spec.passes(q, Spec.passes(p, xs)), passes_add(q, p, xs))
802
803# block_sum: r + p passes over the row are r passes over what its first p passes leave (passes_add), which is its k
804# blocks summed as bal sums them (blocks_passes)
805def Laws.block_sum(p, k, r):
806  +row = Spec.blocks(0n, Nat.mul(Spec.pw(p), k), 0n)
807  Equal.trans(List<&2, Spec.Sum>, Spec.passes(Nat.add(r, p), row), Spec.passes(r, Spec.passes(p, row)), Spec.passes(r, Spec.blocks(p, k, 0n)),
808    passes_add(r, p, row),
809    Equal.cong(List<&2, Spec.Sum>, List<&2, Spec.Sum>, z => Spec.passes(r, z), Spec.passes(p, row), Spec.blocks(p, k, 0n), blocks_passes(p, k, 0n)))
810
811def main() -> Unit:
812  Unit{}