The truth about some Post numbers
- 12 March 1976
- journal article
- Published by Cambridge University Press (CUP) in The Journal of Symbolic Logic
- Vol. 41 (1) , 239-244
- https://doi.org/10.2307/2272964
Abstract
There is a mistake in [6], discovered by Robert V. Kohn: contrary to the claim on p. 714, the set {◊Xi: i ≥ 2} is not independent in S3. As a result three problems thought to be settled are open once more, viz., whether the Post numbers of S2, S3, and K4 are denumerable. In [6] it was claimed they are not. Now we shall prove that that claim is indeed correct for S2 and K4 but, surprisingly enough, not for S3.Keywords
This publication has 2 references indexed in Scilit:
- Post Completeness and UltrafiltersMathematical Logic Quarterly, 1974
- Consistent, independent, and distinct propositions.Notre Dame Journal of Formal Logic, 1972