14
Godel’s Completeness Result
•
Theorem
(soundness) If
G
`
f
then
G
²
f
•
•
Theorem
(completeness) If
G
²
f
then
G
`
f
Which one is easy / hard ?
It follows that
G
²
f
is r.e.
Note: we always assume that
G
is r.e.