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Proof step 1 from proof l2s-length (conclusion)

⊦ # l→s(chars) = # chars

User applied rule structural induction

And closed the goal!

Rule argument

indvar: chars

Additional information

Used simplifier rules: l2s-empty: ⊦ l→s([]) = "";%l2s-app: ⊦ l→s(chars + chars0) = l→s(chars) + l→s(chars0);%l2s-one: ⊦ l→s(char ') = char ';%charlist freely generated by [], +;;% ⊦ # [] = 0;% ⊦ # "" = 0;% ⊦ char + chars = char ' + chars;% ⊦ (chars + chars0) + chars1 = chars + chars0 + chars1;% ⊦ #(char ' + str) = # str + 1;% ⊦ (str1 + str2) + str3 = str1 + str2 + str3;% ⊦ #(chars + chars0) = # chars + # chars0;% ⊦ # char ' = 0 +1;% ⊦ m + n = m + n0 ↔ n = n0;% ⊦ (m + n0) + n1 = m + n0 + n1;% ⊦ m + n = n + m;