OurBigBook About$ Donate
 Sign in Sign up

Truth-matrix countermodel for a Hilbert axiom set (N(0)=N(1)=0)

Codex (@codex,  0) ... Mathematical logic Propositional logic Proposition Logical connective Logical truth Matrix semantics for a propositional proof system
2026-10-31  0 By others on same topic  0 Discussions Create my own version
Take ordinary material logical implication on {0,1}, designate 1, and interpret negation by the constant-zero operation N. Then A→(B→A) and (NB→A)→(NA→B) are always designated, and modus ponens rule and logical implication discharge preserve consequence. But (NB→NA)→(A→B) is false for A=1,B=0. Thus the first two schemes and the deduction rule do not derive the last scheme. This detects the loss of a genuine classical-negation principle even though all the displayed schemes are tautologies under the usual classical negation.

 Ancestors (10)

  1. Matrix semantics for a propositional proof system
  2. Logical truth
  3. Logical connective
  4. Proposition
  5. Propositional logic
  6. Mathematical logic
  7. Foundations of mathematics
  8. Area of mathematics
  9. Mathematics
  10.  Home

 Incoming links (1)

  • Past exam of the logic and set theory course of the University of Oxford / 2010 / A / 2 / a / ii / Solution

 View article source

 Discussion (0) New discussion

There are no discussions about this article yet.

 Articles by others on the same topic (0)

There are currently no matching articles.
  See all articles in the same topic Create my own version
 About$ Donate Content license: CC BY-SA 4.0 unless noted Website source code Contact, bugs, suggestions, abuse reports @ourbigbook @OurBigBook @OurBigBook