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Proof step 191 from proof n2s-s2n-identity (previous step)

∀ m1. m1 < (((((((1 + 1) + 1) + 1) + 1) + 1) + 1) + 1) + 1 → true → s→n(n→s(m1)) = m1 ⊦ 2 = pos('9', '7' ' + '8' ' + '9' ')

User applied rule insert rewrite lemma

And obtained the following new goals

Proof step 192:
⊦ char ≠ char0 → pos(char, char0 ' + chars) = pos(char, chars) + 1
Proof step 193:
'9' ≠ '7', ∀ m1. m1 < (((((((1 + 1) + 1) + 1) + 1) + 1) + 1) + 1) + 1 → true → s→n(n→s(m1)) = m1 ⊦ 2 = pos('9', '8' ' + '9' ') + 1

Rule argument

spec: list-del inst: charlist name: pos-n seq: ⊦ char ≠ char0 → pos(char, char0 ' + chars) = pos(char, chars) + 1 subst: [chars, char0, char] → ['8' ' + '9' ', '7', '9'] flags: rewrite

Additional information

Used terms: '8' ' + '9' ', '7', '9'