the North is not a kind of a crystal.
sent1: the North is a crystal if the tilth is unrespectable. sent2: if the edging is not overt that the tilth is not non-alabaster and not unrespectable is false. sent3: the tilth is overt. sent4: the North is unrespectable if that it is a crystal is true. sent5: if the tilth is not a kind of an alabaster and is not unrespectable then it is not overt. sent6: the fact that the tilth is not alabaster and it is not unrespectable if the North is unrespectable is correct.
void -> assump1: Let's assume that the North is a crystal.; sent4 & assump1 -> int1: the North is unrespectable.; int1 & sent6 -> int2: the tilth is not an alabaster and is not unrespectable.; int2 & sent5 -> int3: the tilth is not overt.; int3 & sent3 -> int4: this is contradiction.; [assump1] & int4 -> hypothesis;
the North is a crystal.
$hypothesis$ = the North is not a kind of a crystal. ; $context$ = sent1: the North is a crystal if the tilth is unrespectable. sent2: if the edging is not overt that the tilth is not non-alabaster and not unrespectable is false. sent3: the tilth is overt. sent4: the North is unrespectable if that it is a crystal is true. sent5: if the tilth is not a kind of an alabaster and is not unrespectable then it is not overt. sent6: the fact that the tilth is not alabaster and it is not unrespectable if the North is unrespectable is correct. ; $proof$ = 
void -> assump1: Let's assume that the North is a crystal.; sent4 & assump1 -> int1: the North is unrespectable.; int1 & sent6 -> int2: the tilth is not an alabaster and is not unrespectable.; int2 & sent5 -> int3: the tilth is not overt.; int3 & sent3 -> int4: this is contradiction.; [assump1] & int4 -> hypothesis; __PROVED__