free algebras via a functor
play

Free algebras via a functor Sam van Gool on partial algebras Free - PowerPoint PPT Presentation

Free algs via functor on partial algs Dion Coumans and Free algebras via a functor Sam van Gool on partial algebras Free algebra step-by-step Free image-total functor Dion Coumans and Sam van Gool Application to KB Topology,


  1. Free alg’s via functor on partial alg’s Dion Coumans and Free algebras via a functor Sam van Gool on partial algebras Free algebra step-by-step Free image-total functor Dion Coumans and Sam van Gool Application to KB Topology, Algebra and Categories in Logic (TACL) 26 – 30 July 2011 Marseilles, France 1 / 16

  2. Free alg’s via functor on Logic via algebra partial alg’s Dion Coumans and Sam van Gool • Algebraic logic L , signature σ , variety V L of σ -algebras Free algebra step-by-step Free image-total functor Application to KB 2 / 16

  3. Free alg’s via functor on Logic via algebra partial alg’s Dion Coumans and Sam van Gool • Algebraic logic L , signature σ , variety V L of σ -algebras Free algebra • Studying the logic L � Studying finitely generated free step-by-step V L -algebras Free image-total functor Application to KB 2 / 16

  4. Free alg’s via functor on Logic via algebra partial alg’s Dion Coumans and Sam van Gool • Algebraic logic L , signature σ , variety V L of σ -algebras Free algebra • Studying the logic L � Studying finitely generated free step-by-step V L -algebras Free image-total functor Application to KB F σ ( x 1 , . . . , x m ) Language 2 / 16

  5. Free alg’s via functor on Logic via algebra partial alg’s Dion Coumans and Sam van Gool • Algebraic logic L , signature σ , variety V L of σ -algebras Free algebra • Studying the logic L � Studying finitely generated free step-by-step V L -algebras Free image-total functor Application to KB F σ ( x 1 , . . . , x m ) Language [ · ] ⊣⊢ L F V L ( x 1 , . . . , x m ) Logic 2 / 16

  6. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool Free algebra step-by-step • In many cases, a variety ( V L ) − of reducts is Free image-total well-understood and locally finite, e.g.: functor Application to KB 3 / 16

  7. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool Free algebra step-by-step • In many cases, a variety ( V L ) − of reducts is Free image-total well-understood and locally finite, e.g.: functor Application to • Modal algebras = Boolean algebras + � , KB 3 / 16

  8. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool Free algebra step-by-step • In many cases, a variety ( V L ) − of reducts is Free image-total well-understood and locally finite, e.g.: functor Application to • Modal algebras = Boolean algebras + � , KB • Heyting algebras = Distributive lattices + → , 3 / 16

  9. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool Free algebra step-by-step • In many cases, a variety ( V L ) − of reducts is Free image-total well-understood and locally finite, e.g.: functor Application to • Modal algebras = Boolean algebras + � , KB • Heyting algebras = Distributive lattices + → , • . . . 3 / 16

  10. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool Free algebra step-by-step • In many cases, a variety ( V L ) − of reducts is Free image-total well-understood and locally finite, e.g.: functor Application to • Modal algebras = Boolean algebras + � , KB • Heyting algebras = Distributive lattices + → , • . . . • Regard F V L ( x 1 , . . . , x n ) as colimit of a chain of finite algebras in the reduced signature, and add the additional operation(s) step-by-step: 3 / 16

  11. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB Logic 4 / 16

  12. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool T 0 Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f 4 / 16

  13. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool T 0 Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB B 0 Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  14. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool T 0 T 1 Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB B 0 Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  15. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool T 0 T 1 Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB B 0 B 1 Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  16. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · T 0 T 1 Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · B 0 B 1 Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  17. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · T 0 T 1 T n Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · B 0 B 1 B n Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  18. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · · · · T 0 T 1 T n Language Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · · · · B 0 B 1 B n Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  19. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · · · · T 0 T 1 T n Language f Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · · · · B 0 B 1 B n Logic • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  20. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · · · · T 0 T 1 T n Language f Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · · · · B 0 B 1 B n Logic f • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  21. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · · · · T 0 T 1 T n Language f f f Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · · · · B 0 B 1 B n Logic f f f • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n 4 / 16

  22. Free alg’s via functor on Free algebra as colimit of a chain partial alg’s Dion Coumans and Sam van Gool · · · · · · T 0 T 1 T n Language f f f Free algebra step-by-step Free image-total [ · ] ⊣⊢ L functor Application to KB · · · · · · B 0 B 1 B n Logic f f f • T n : formulas in variables x 1 , . . . , x m of rank ≤ n in operation f • B n : L -equivalence classes of formulas in T n F V L ( x 1 , . . . , x m ) = colim n ≥ 0 B n 4 / 16

  23. Free alg’s via functor on Research Question partial alg’s Dion Coumans and Sam van Gool Free algebra · · · · · · B 0 B 1 B n step-by-step Free image-total functor Application to Can B n + 1 be obtained from B n by a uniform method? KB 5 / 16

  24. Free alg’s via functor on Research Question partial alg’s Dion Coumans and Sam van Gool Free algebra · · · · · · B 0 B 1 B n step-by-step Free image-total functor Application to Can B n + 1 be obtained from B n by a uniform method? KB • Yes, if the variety is defined by pure rank 1 equations [N. Bezhanishvili, Kurz] 5 / 16

  25. Free alg’s via functor on Research Question partial alg’s Dion Coumans and Sam van Gool Free algebra · · · · · · B 0 B 1 B n step-by-step Free image-total functor Application to Can B n + 1 be obtained from B n by a uniform method? KB • Yes, if the variety is defined by pure rank 1 equations [N. Bezhanishvili, Kurz] • Yes, in some particular cases outside this class: S4 modal algebras [Ghilardi], Heyting algebras [Ghilardi, N. Bezhanishvili & Gehrke]. 5 / 16

Download Presentation
Download Policy: The content available on the website is offered to you 'AS IS' for your personal information and use only. It cannot be commercialized, licensed, or distributed on other websites without prior consent from the author. To download a presentation, simply click this link. If you encounter any difficulties during the download process, it's possible that the publisher has removed the file from their server.

Recommend


More recommend