Appl Categor Struct
DOI 10.1007/s10485-016-9427-1
Prolongations, Suspensions and Telescopes
Jaime Mart´ ın Fern´ andez Cestau
1
·
Luis Javier Hern´ andez Paricio
1
·
Mar´ ıa Teresa Rivas Rodr´ ıguez
1
Received: 10 May 2013 / Accepted: 25 January 2016
© Springer Science+Business Media Dordrecht 2016
Abstract Autonomous differential equations induced by continuous vector fields usually
appear in non-smooth mechanics and other scientific contexts. For these type of equations,
given an initial condition, one has existence theorems but, in general, the uniqueness of
the solution can not be ensured. For continuous vector fields, the equation solutions do not
generally present a continuous flow structure; one particular but interesting case, occurs
when under some initial conditions one can ensure existence of solutions and uniqueness
in forward time obtaining in this case continuous semi-flows. The discretization and return
Poincar´ e techniques induce the corresponding discrete flows and semi-flows and some
inverse methods as the suspension can construct a flow from a discrete flow or semi-flow.
The objective of this work is to give categorical models for the diverse phase spaces of
continuous and discrete semi-flows and flows and for the relations between these differ-
ent phase spaces. We also introduce some new constructions such as the prolongation of
continuous and discrete semi-flows and the telescopic functors. We consider small Top-
categories (weakly enriched over the category Top of topological spaces) and we take as
categorical models of the solutions of these differential equations some categories of con-
tinuous functors from a small Top-category to the category of topological spaces. Moreover,
the processes of discretizations, suspensions, prolongations, et cetera are described in terms
of adjoint functors. The main contributions of this paper are the construction of a tensor
product associated to a functor between small Top-categories and the interpretation of pro-
longations, suspensions and telescopes as particular cases of this general tensor product.
In general, the paper is focused on the establishment of links between category theory and
Luis Javier Hern´ andez Paricio
luis-javier.hernandez@unirioja.es
Jaime Mart´ ın Fern´ andez Cestau
fdezcestau@gmail.com
Mar´ ıa Teresa Rivas Rodr´ ıguez
maria-teresa.rivas@unirioja.es
1
Departamento de Matem´ aticas y Computaci ´ on, Universidad de La Rioja, 26004 Logro˜ no, Spain