TY - JOUR

T1 - Lawvere theories, finitary monads and Cauchy-completion

AU - Garner, Richard

PY - 2014/11

Y1 - 2014/11

N2 - We consider the equivalence of Lawvere theories and finitary monads on Set from the perspective of F-enriched category theory, where F is the monoidal category of finitary endofunctors of Set under composition. We identify finitary monads with one-object F-categories, and ordinary categories admitting finite powers (i.e., n-fold products of each object with itself) with F-categories admitting a certain class Φ of absolute colimits; we then show that, from this perspective, the passage from a finitary monad to the associated Lawvere theory is given by completion under Φ-colimits. We also account for other phenomena from the enriched viewpoint: the equivalence of the algebras for a finitary monad with the models of the corresponding Lawvere theory; the functorial semantics in arbitrary categories with finite powers; and the existence of left adjoints to algebraic functors.

AB - We consider the equivalence of Lawvere theories and finitary monads on Set from the perspective of F-enriched category theory, where F is the monoidal category of finitary endofunctors of Set under composition. We identify finitary monads with one-object F-categories, and ordinary categories admitting finite powers (i.e., n-fold products of each object with itself) with F-categories admitting a certain class Φ of absolute colimits; we then show that, from this perspective, the passage from a finitary monad to the associated Lawvere theory is given by completion under Φ-colimits. We also account for other phenomena from the enriched viewpoint: the equivalence of the algebras for a finitary monad with the models of the corresponding Lawvere theory; the functorial semantics in arbitrary categories with finite powers; and the existence of left adjoints to algebraic functors.

UR - http://www.scopus.com/inward/record.url?scp=84901420761&partnerID=8YFLogxK

U2 - 10.1016/j.jpaa.2014.02.018

DO - 10.1016/j.jpaa.2014.02.018

M3 - Article

AN - SCOPUS:84901420761

VL - 218

SP - 1973

EP - 1988

JO - Journal of Pure and Applied Algebra

JF - Journal of Pure and Applied Algebra

SN - 0022-4049

IS - 11

ER -