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INTERDEFINABILITY OF LAMBEKIAN FUNCTORS
Author(s) -
Zielonka Wojciech,
Zielonka W.
Publication year - 1992
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/malq.19920380145
Subject(s) - sequent , functor , hierarchy , mathematics , sequent calculus , pure mathematics , product (mathematics) , derived functor , algebra over a field , calculus (dental) , discrete mathematics , geometry , medicine , dentistry , economics , mathematical proof , market economy
Several Gentzen‐style (sequential) syntactic type calculi with product(s) are considered. They form a hierarchy in such a way that one calculus results from another by imposing a new condition (expressed in terms of “structural rules”) upon the sequent‐forming operation. It turns out that, at some steps of this process, two different functors collapse to a single one. For the remaining stages of the hierarchy, analogues of Wajsbergs's theorem on non‐mutual‐definability are proved.