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Proof step 5 from proof bytes2int-neg (previous step)

∀ bytes0. # bytes0 < #(by + bytes1) → true → bytes0 ≠ [] → (bytes2int(bytes0) < 0 ↔ b2i(bytes0.first) < 0) ⊦ bytes2int(by ' + bytes1) < 0 ↔ ¬ 0 ≤ b2i(by)

User applied rule insert rewrite lemma

And obtained the following new goals

Proof step 6:
⊦ 1 < # bytes → bytes2int(bytes) = bytes2int(bytes.butlast) * 256 + band(b2i(bytes.last), 255)
Proof step 7:
1 < #(by ' + bytes1), ∀ bytes0. # bytes0 < #(by + bytes1) → true → bytes0 ≠ [] → (bytes2int(bytes0) < 0 ↔ b2i(bytes0.first) < 0) ⊦ bytes2int((by ' + bytes1).butlast) * 256 + band(b2i((by ' + bytes1).last), 255) < 0 ↔ ¬ 0 ≤ b2i(by)

Rule argument

name: bytes2int-rec-01 rotate: F subst: [bytes] → [by ' + bytes1]

Additional information

Used simplifier rules: bytes2int-one: ⊦ bytes2int(by ') = b2i(by);% ⊦ #(bytes + bytes0) = # bytes + # bytes0;% ⊦ # by ' = 0 +1;% ⊦ (bytes + bytes0) + bytes1 = bytes + bytes0 + bytes1;% ⊦ 1 < m ↔ ¬(m = 0 ∨ m = 1);% ⊦ m + 1 ≠ 0;% ⊦ (m + n0) + n1 = m + n0 + n1;% ⊦ m + n = n + m;% ⊦ 1 = m + 1 ↔ m = 0;% ⊦ # bytes = 0 ↔ bytes = [];% ⊦ bytes + [] = bytes;% ⊦ i ≤ j → (¬ ¬ j < i ↔ false);% ⊦ ¬ i ≤ j ↔ j < i;% ⊦ ¬ i < j ↔ j ≤ i;% ⊦ i < j → (¬ ¬ j ≤ i ↔ false); Used terms: by ' + bytes1