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Recent Posts
 Incredibly awesome, but with overlength September 3, 2021
 Fields and total orders are the prime objects of nice categories January 30, 2021
 Prefixfree codes and ordinals May 11, 2020
 Isomorphism of labeled uniqueness trees April 20, 2020
 Defining a natural number as a finite string of digits is circular August 17, 2019
 Theory and practice of signeddigit representations April 16, 2019
 A list of books for understanding the nonrelativistic QM — Ajit R. Jadhav’s Weblog November 25, 2018
 I’m not a physicist April 29, 2018
 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
Recent Comments
 Fields and total orders are the prime objects of nice categories  Gentzen translated on Defining a natural number as a finite string of digits is circular
 Fields and total orders are the prime objects of nice categories  Gentzen translated on Algebraic characterizations of inverse semigroups and strongly regular rings
 gentzen on ALogTime, LogCFL, and threshold circuits: dreams of fast solutions
 gentzen on Theory and practice of signeddigit representations
 gentzen on Defining a natural number as a finite string of digits is circular
 gentzen on Defining a natural number as a finite string of digits is circular
 gentzen on Theory and practice of signeddigit representations
 rjlipton on Theory and practice of signeddigit representations
 Defining a natural number as a finite string of digits is circular  Gentzen translated on Theory and practice of signeddigit representations
 Theory and practice of signeddigit representations  Gentzen translated on ALogTime, LogCFL, and threshold circuits: dreams of fast solutions
 Ajit R. Jadhav on A list of books for understanding the nonrelativistic QM — Ajit R. Jadhav’s Weblog
 gentzen on I’m not a physicist
 gentzen on ALogTime, LogCFL, and threshold circuits: dreams of fast solutions
 gentzen on ALogTime, LogCFL, and threshold circuits: dreams of fast solutions
 gentzen on ALogTime, LogCFL, and threshold circuits: dreams of fast solutions
Category Archives: logic
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