theorem :: SF_MASTR:51

for a, b being Int-Location
for p being preProgram of SCM+FSA st ( a := b in rng p or AddTo (a,b) in rng p or SubFrom (a,b) in rng p or MultBy (a,b) in rng p or Divide (a,b) in rng p ) holds
( FirstNotUsed p <> a & FirstNotUsed p <> b )