| ⊦ char ' + str0 = "", l→s(sublist(m0 + 1, n, char ' + s→l(str0))) = substring(str0, m0, n) |
⊦ sublist(m + 1, n, chars) = sublist(m, n, chars.rest)
⊦ char ' + str0 = "", l→s(sublist(m0, n, (char ' + s→l(str0)).rest)) = substring(str0, m0, n)
Used terms: char ' + s→l(str0), n, m0