Logica
Tools
for
Thought
Hilbert
Copy
Load
Save
Library
Objects
a, b, c
Functions
f, g
1
p => q
Premise
2
q => ~~q
Negation Introduction Schema
3
p => ~~q
Transitivity
1
2
4
~q => ~q
Identity Schema
5
~q => ~p
Contradiction
4
3
