Extensive categories, commutative semirings and Galois theory

We describe the Galois theory of commutative semirings as a Boolean Galois theory in the sense of Carboni and Janelidze. Such a Galois structure then naturally suggests an extension to commutative semirings of the classical theory of quadratic equations over commutative rings. We show, however, that our proposed generalization is impossible for connected commutative semirings which are not rings, leading to the conclusion that for the theory of quadratic equations, “minus is needed”. Finally, by considering semirings B which have no non-trivial additive inverses and no non-trivial zero divisors, we present an example of a normal extension of commutative semirings which has an underlying B-semimodule structure isomorphic to B×B.

Grantor

Department of Mathematics and Applied Mathematics

Year dc:date.issued

2020

Author dc:creator

• Poklewski-Koziell, Rowan

Advisor dc:contributor.advisor

• Janelidze, George

• Applied Mathematics

Handle dc:identifier.uri

http://hdl.handle.net/11427/32412

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/32412