Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
Drexel University or The Math Forum.



Re: SCI.LOGIC is a STAGNANT CESS PITT of LOSERS!
Posted:
Nov 17, 2012 4:36 PM


On Nov 18, 4:24 am, Frederick Williams <freddywilli...@btinternet.com> wrote: > Graham Cooper wrote: > > > FROM AXIOMS you DERIVE THEOREMS! > > > Nobody CARES if SomeModel = 'this is not derivable from your > > axioms" > > > looks TRUE! > > > IT's not DERIVABLE FROM THE AXIOMS! END OF STORY! > > How do you show that some formula (phi, let's say) is not derivable from > the axioms? >
You start with a naive specification of DERIVE(THEOREM)
You gave a rudimentary description of the method at one point, see how you go!
Herc 
TAUTOLOGIES A B T TYPE a a>c c Modus Ponens d>e e>f d>f Transitivity !(!d) TRUE d Double Negation ... LOGIC E(Y) Y={xP(x)} <> DERIVE( E(Y) Y={xP(x)} ) DERIVE(T) <> DERIVE(a) ^ DERIVE(b) ^ (a^b)>T MATHEMATICS E(Y) Y={xP(x)} <> PRVBLE( E(Y) Y={xP(x)} ) PRVBLE(T) <> NOT(DERIVE(NOT(T)))



