| i = intfun(i0), i = intfun(i0) ∨ i ∈ mapFun(intfun, ints0), i ∈ mapFun(intfun, ints0) ↔ (∃ j. j ∈ ints0 ∧ intfun(j) = i), ∀ i, intfun. i ∈ mapFun(intfun, ints0) ↔ (∃ j. j ∈ ints0 ∧ intfun(j) = i) ⊦ ∃ j. (j = i0 ∨ j ∈ ints0) ∧ intfun(j) = i |
intfun(i0) ∈ mapFun(intfun, ints0) ↔ (∃ j. j ∈ ints0 ∧ intfun(j) = intfun(i0)), ∀ i, intfun. i ∈ mapFun(intfun, ints0) ↔ (∃ j. j ∈ ints0 ∧ intfun(j) = i) ⊦ ∃ j. (j = i0 ∨ j ∈ ints0) ∧ intfun(j) = intfun(i0)