Title
Functorial boxes in string diagrams
Abstract
String diagrams were introduced by Roger Penrose as a handy notation to manipulate morphisms in a monoidal category. In principle, this graphical notation should encompass the various pictorial systems introduced in proof-theory (like Jean-Yves Girard’s proof-nets) and in concurrency theory (like Robin Milner’s bigraphs). This is not the case however, at least because string diagrams do not accomodate boxes — a key ingredient in these pictorial systems. In this short tutorial, based on our accidental rediscovery of an idea by Robin Cockett and Robert Seely, we explain how string diagrams may be extended with a notion of functorial box depicting a functor transporting an inside world (its source category) to an outside world (its target category). We expose two elementary applications of the notation: first, we characterize graphically when a faithful balanced monoidal functor F:ℂ $\longrightarrow$$\mathbb{D}$ transports a trace operator from the category $\mathbb{D}$ to the category ℂ, and exploit this to construct well-behaved fixpoint operators in cartesian closed categories generated by models of linear logic; second, we explain how the categorical semantics of linear logic induces that the exponential box of proof-nets decomposes as two enshrined boxes.
Year
DOI
Venue
2006
10.1007/11874683_1
CSL
Keywords
Field
DocType
source category,handy notation,graphical notation,linear logic,string diagram,functorial box,robin milner,robin cockett,monoidal category,enshrined box,target category,proof theory
Cone (category theory),Closed monoidal category,Discrete mathematics,Enriched category,Monoidal functor,Closed category,Monoidal category,Symmetric monoidal category,Concrete category,Mathematics
Conference
Volume
ISSN
ISBN
4207
0302-9743
3-540-45458-6
Citations 
PageRank 
References 
12
0.69
17
Authors
1
Name
Order
Citations
PageRank
Paul-andré Melliès139230.70