SD
A system for testing entailments in SL
Natural deduction
breaks down premise into simple steps
Derivable (P is derivable from \gamma, \gamma |- P)
If a derivation occurs where:
SD is sound
If \gamma |- P (derivable in SD), \gamma |= P (TF entails P)
SD is complete
if \gamma |= P (TF entails), \gamma |- P (derivable in SD)
Theorem
A sentence that can be constructed from the empty set
Equivalence in SD
{P} |- Q and {Q} |- P (P === Q)
Inconsistency in SD (\gamma is inconsistent)
\gamma |- P and \gamma |- ~P or…
\gamma entails every sentence
principle of explosion
From a contradiction you can entail every sentence