Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Retractions in Intersection Types   This paper deals with retraction - intended as isomorphic embedding - in
intersection types building left and right inverses as terms of a lambda
calculus with a bottom constant. The main result is a necessary and sufficient
condition two strict intersection types must satisfy in order to assure the
existence of two terms showing the first type to be a retract of the second
one. Moreover, the characterisation of retraction in the standard intersection
types is discussed.

28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex