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Proof step 13 from proof fix2rest-last (previous step)

2 < # bytes ⊦ lastn(2, bytes).rest = bytes.last ', bytes = []

User applied rule insert rewrite lemma

And obtained the following new goals

Proof step 14:
⊦ n ≠ 0 → lastn(n, bytes) = lastn(n -1, bytes.butlast) + bytes.last

Rule argument

seq: ⊦ n ≠ 0 → lastn(n, bytes) = lastn(n -1, bytes.butlast) + bytes.last subst: [bytes, n] → [bytes, 2] rotate: F spec: list-del inst: bytelist name: lastn-rec

Additional information

Used simplifier rules: ⊦ lastn(1, bytes) = bytes.last ';% ⊦ bytes + by = bytes + by ';% ⊦ (by ' + bytes).rest = bytes;% ⊦ (bytes + bytes0) + bytes1 = bytes + bytes0 + bytes1;% ⊦ by ' = by0 ' ↔ by = by0; Used terms: bytes, 2