Blogs I Follow

Recent Posts
 ALogTime, LogCFL, and threshold circuits: dreams of fast solutions November 2, 2017
 A subset interpretation (with context morphisms) of the sequent calculus for predicate logic September 24, 2017
 Logic without negation and falsehood December 11, 2016
 Logic without truth September 3, 2016
 Learning category theory: a necessary evil? April 3, 2016
 A canonical labeling technique by Brendan McKay and isomorphism testing of deterministic finite automata November 15, 2015
 On Zeros of a Polynomial in a Finite Grid: the AlonFuredi bound September 19, 2015
 Groupoids August 3, 2015
 Reversibility of binary relations, substochastic matrices, and partial functions March 22, 2015
 Algebraic characterizations of inverse semigroups and strongly regular rings December 6, 2014
 Gentzen’s consistency proof is more impressive than you expect December 5, 2013
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 gentzen on ALogTime, LogCFL, and threshold circuits: dreams of fast solutions
 A subset interpretation (with context morphisms) of the sequent calculus for predicate logic  Gentzen translated on Logic without truth
 A subset interpretation (with context morphisms) of the sequent calculus for predicate logic  Gentzen translated on Logic without negation and falsehood
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 Logic without negation and falsehood  Gentzen translated on Logic without truth
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 gentzen on Logic without truth
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 gentzen on Logic without truth
 Learning category theory: a necessary evil?  Gentzen translated on A canonical labeling technique by Brendan McKay and isomorphism testing of deterministic finite automata
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 gentzen on A canonical labeling technique by Brendan McKay and isomorphism testing of deterministic finite automata
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Tag Archives: gentzen
A subset interpretation (with context morphisms) of the sequent calculus for predicate logic
The previous two posts used the sequent calculus with a subset interpretation: We work with sequents , and interpret the propositions (and ) as subsets of some universe set . We interpret the sequent itself as . While writing the … Continue reading
Logic without negation and falsehood
In the last post, consideration related to partial functions lead us to present a logic without truth and implication, using the binary minus operation as a dual of implication and substitute for unary negation. But logic without implication and equivalence … Continue reading
Logic without truth
Pi is wrong! But so what? It is neither new, nor complicated enough to count as real math! And suggestions that or might be even better show that it not clearcut either. I recently invested sufficient energy into some logical questions to … Continue reading
Gentzen’s consistency proof is more impressive than you expect
I recently said something about the impossibility to prove the consistency of PA, and that Gentzen proved just this in 1936. Because I got critizised quite a bit, and realized that even famous mathematicians get critizized if they dare to … Continue reading