Multiversal Polymorphic Algebraic Theories: Syntax, Semantics, Translations, and Equational Logic

Author(s):  
Marcelo Fiore ◽  
Makoto Hamana
Author(s):  
Marc Bezem ◽  
Thierry Coquand ◽  
Peter Dybjer ◽  
Martín Escardó

Abstract We give a syntax independent formulation of finitely presented generalized algebraic theories as initial objects in categories of categories with families (cwfs) with extra structure. To this end, we simultaneously define the notion of a presentation Σ of a generalized algebraic theory and the associated category CwFΣ of small cwfs with a Σ-structure and cwf-morphisms that preserve Σ-structure on the nose. Our definition refers to the purely semantic notion of uniform family of contexts, types, and terms in CwFΣ. Furthermore, we show how to syntactically construct an initial cwf with a Σ-structure. This result can be viewed as a generalization of Birkhoff’s completeness theorem for equational logic. It is obtained by extending Castellan, Clairambault, and Dybjer’s construction of an initial cwf. We provide examples of generalized algebraic theories for monoids, categories, categories with families, and categories with families with extra structure for some type formers of Martin-Löf type theory. The models of these are internal monoids, internal categories, and internal categories with families (with extra structure) in a small category with families. Finally, we show how to extend our definition to some generalized algebraic theories that are not finitely presented, such as the theory of contextual cwfs.


1982 ◽  
Vol 5 (2) ◽  
pp. 171-186
Author(s):  
Stephen L. Bloom
Keyword(s):  

A review is given of some of the late C.C. Elgot’s ideas on the syntax and semantics of monadic flowchart algorithms. In particular, the motivation for his “iterative algebraic theories” is explained.


1987 ◽  
Vol 22 (4) ◽  
pp. 41-48 ◽  
Author(s):  
J A Goguen ◽  
J Meseguer
Keyword(s):  

1991 ◽  
Vol 15 (1) ◽  
pp. 80-85
Author(s):  
P.H. Rodenburg

In a natural formulation, Craig’s interpolation theorem is shown to hold for conditional equational logic.


1982 ◽  
Vol 17 (1) ◽  
pp. 9-17 ◽  
Author(s):  
J. A. Goguen ◽  
J. Meseguer
Keyword(s):  

2011 ◽  
Vol 21 (5) ◽  
pp. 1035-1066 ◽  
Author(s):  
Z. ÉSIK ◽  
T. HAJGATÓ

Partial iterative theories are algebraic theories such that for certain morphisms f the equation ξ = f ⋅ 〈ξ, 1p〉 has a unique solution. Iteration theories are algebraic theories satisfying a certain set of identities. We investigate some similarities between partial iterative theories and iteration theories.In our main result, we give a sufficient condition ensuring that the partially defined dagger operation of a partial iterative theory can be extended to a totally defined operation so that the resulting theory becomes an iteration theory. We show that this general extension theorem can be instantiated to prove that every Elgot iterative theory with at least one constant morphism 1 → 0 can be extended to an iteration theory. We also apply our main result to theories equipped with an additive structure.


2002 ◽  
Vol 41 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Radim Bělohlávek
Keyword(s):  

2011 ◽  
pp. 10-20
Author(s):  
J. Adamek ◽  
J. Rosicky ◽  
E. M. Vitale ◽  
F. W. Lawvere
Keyword(s):  

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