Exercise 8.2

Fitch

Goal

Incomplete

Enter the premise you wish to add to the proof:

Enter the assumption you wish to make:

Enter the conclusion you wish to add to the proof:

Enter the justification for this conclusion:

Enter the sentence you wish to disjoin to the checked items:

Or Elimination:

φ∨ψ
φ⇒χ
ψ⇒χ

χ

Universal Introduction:

φ

Aν:φ

Enter the variable you would like to use:

ν:

Universal Elimination:

Aν:φ

φ[ν←τ]
where τ is free for ν in φ

Enter the term you would like to use:

τ:

Existential Introduction:

φ(τ)

Eν:φ(ν)

Enter the term you would like to replace:

τ:

Enter the variable you would like to use:

ν:

Equality Introduction:

τ=τ

Enter the term you would like to use:

τ: