4 papers
Infinitely ludic categories
Matheus Duzi, Paul Szeptycki, Walter Tholen
Pursuing a new approach to the study of infinite games in combinatorics, we introduce the categories and and improve some classical results…
Quotients of span categories that are allegories and the representation of regular categories
S. Naser Hosseini, Amir R. Shir Ali Nasab, Walter Tholen +1
We consider the ordinary category Span(C) of (isomorphism classes of) spans of morphisms in a category C with finite limits as needed, composed horizontally via pullback, and give…
Fraction, Restriction and Range Categories from Non-Monic Classes of Morphisms
S. N. Hosseini, A. R. Shir Ali Nasab, W. Tholen
For a composition-closed and pullback-stable class S of morphisms in a category C containing all isomorphisms, we form the category Span(C,S) of S-spans (s,f) in C with first "leg"…
Extensions of dualities and a new approach to the Fedorchuk duality
G. Dimov, E. Ivanova-Dimova, W. Tholen
Applying a general categorical construction for the extension of dualities, we present a new proof of the Fedorchuk duality between the category of compact Hausdorff spaces with th…