On the structure of halfdiagonal-halfterminal-symmetric categories with diagonal inversions

Hans-Jürgen Vogel

Discussiones Mathematicae - General Algebra and Applications (2001)

  • Volume: 21, Issue: 2, page 139-163
  • ISSN: 1509-9415

Abstract

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The category of all binary relations between arbitrary sets turns out to be a certain symmetric monoidal category Rel with an additional structure characterized by a family d = ( d A : A A A | A | R e l | ) of diagonal morphisms, a family t = ( t A : A I | A | R e l | ) of terminal morphisms, and a family = ( A : A A A | A | R e l | ) of diagonal inversions having certain properties. Using this properties in [11] was given a system of axioms which characterizes the abstract concept of a halfdiagonal-halfterminal-symmetric monoidal category with diagonal inversions (hdht∇s-category). Besides of certain identities this system of axioms contains two identical implications. In this paper is shown that there is an equivalent characterizing system of axioms for hdht∇s-categories consisting of identities only. Therefore, the class of all small hdht∇-symmetric categories (interpreted as hetrogeneous algebras of a certain type) forms a variety and hence there are free theories for relational structures.

How to cite

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Hans-Jürgen Vogel. "On the structure of halfdiagonal-halfterminal-symmetric categories with diagonal inversions." Discussiones Mathematicae - General Algebra and Applications 21.2 (2001): 139-163. <http://eudml.org/doc/287740>.

@article{Hans2001,
abstract = {The category of all binary relations between arbitrary sets turns out to be a certain symmetric monoidal category Rel with an additional structure characterized by a family $d = (d_\{A\}: A → A⨂ A | A ∈ |Rel|)$ of diagonal morphisms, a family $t = (t_\{A\}: A → I | A ∈ |Rel|)$ of terminal morphisms, and a family $∇ = (∇_\{A\}: A ⨂ A → A | A ∈ |Rel|)$ of diagonal inversions having certain properties. Using this properties in [11] was given a system of axioms which characterizes the abstract concept of a halfdiagonal-halfterminal-symmetric monoidal category with diagonal inversions (hdht∇s-category). Besides of certain identities this system of axioms contains two identical implications. In this paper is shown that there is an equivalent characterizing system of axioms for hdht∇s-categories consisting of identities only. Therefore, the class of all small hdht∇-symmetric categories (interpreted as hetrogeneous algebras of a certain type) forms a variety and hence there are free theories for relational structures.},
author = {Hans-Jürgen Vogel},
journal = {Discussiones Mathematicae - General Algebra and Applications},
keywords = {halfdiagonal-halfterminal-symmetric category; diagonal inversion; partial order relation; subidentity; equation; halfdiagonal-halfterminal-symmetric monoidal category; diagonal inversions},
language = {eng},
number = {2},
pages = {139-163},
title = {On the structure of halfdiagonal-halfterminal-symmetric categories with diagonal inversions},
url = {http://eudml.org/doc/287740},
volume = {21},
year = {2001},
}

TY - JOUR
AU - Hans-Jürgen Vogel
TI - On the structure of halfdiagonal-halfterminal-symmetric categories with diagonal inversions
JO - Discussiones Mathematicae - General Algebra and Applications
PY - 2001
VL - 21
IS - 2
SP - 139
EP - 163
AB - The category of all binary relations between arbitrary sets turns out to be a certain symmetric monoidal category Rel with an additional structure characterized by a family $d = (d_{A}: A → A⨂ A | A ∈ |Rel|)$ of diagonal morphisms, a family $t = (t_{A}: A → I | A ∈ |Rel|)$ of terminal morphisms, and a family $∇ = (∇_{A}: A ⨂ A → A | A ∈ |Rel|)$ of diagonal inversions having certain properties. Using this properties in [11] was given a system of axioms which characterizes the abstract concept of a halfdiagonal-halfterminal-symmetric monoidal category with diagonal inversions (hdht∇s-category). Besides of certain identities this system of axioms contains two identical implications. In this paper is shown that there is an equivalent characterizing system of axioms for hdht∇s-categories consisting of identities only. Therefore, the class of all small hdht∇-symmetric categories (interpreted as hetrogeneous algebras of a certain type) forms a variety and hence there are free theories for relational structures.
LA - eng
KW - halfdiagonal-halfterminal-symmetric category; diagonal inversion; partial order relation; subidentity; equation; halfdiagonal-halfterminal-symmetric monoidal category; diagonal inversions
UR - http://eudml.org/doc/287740
ER -

References

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  11. [11] H.-J. V, Relations as morphisms of a certain monoidal category, 'General Algebra and Applications in Discrete Mathematics', Shaker Verlag, Aachen 1997, 205-217. 
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  13. [13] H.-J. V, On Properties of dhtŃ-symmetric categories, Contributions to General Algebra 11 (1999), 211-223. 
  14. [14] H.-J. V, Halfdiagonal-halfterminal-symmetric monoidal categories with inversions, 'General Algebra and Discrete Mathematics', Shaker Verlag, Aachen 1999, 189-204. 
  15. [15] H.-J. V, On morphisms between prtial algebras, 'Algebras and Combinatorics. An International Congress, ICAC '97, Hong Kong', Springer-Verlag, Singapore 1999, 427-453. Zbl0968.08003

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