- #1
nomadreid
Gold Member
- 1,670
- 204
The necessity quantifier (aka Provability quantifier, or ~◊~, or Belief, or... instead of the usual square I will be lazy and call it "N") is often allowed to be repeated as many (finite) times as one wishes, so NNNNNNψ is OK. Is it possible to somehow include into the axioms some restriction on the number of times it can be applied, or even for example outlawing an odd number of applications? My guess is that no, as one would need to have a sentence with too large a domain of the quantifier in the sentence, but I would like to see if my guess is correct.