4 papers
Schrijver-Delsarte rigidity in association schemes and undecidability of quantum graph homomorphism
Lorenzo Ciardo, Iris Hebbeker, Gideo Joubert +2
We prove RE-completeness of the quantum homomorphism problem parameterised by families of graphs derived from the classic metric association schemes. These include Kneser graphs, $…
Quantum Polymorphisms and the Complexity of Quantum Constraint Satisfaction
Lorenzo Ciardo, Gideo Joubert, Antoine Mottet
We introduce the concept of quantum polymorphisms to the complexity theory of quantum constraint satisfaction. Via this notion, we build an algebraic framework of reductions betwee…
The Case for Inverse Semirings
Peter F. Faul, Amartya Goswami, Gideo Joubert +1
A semiring generalises the notion of a ring, replacing the additive abelian group structure with that of a commutative monoid. In this paper, we study a notion positioned between a…
The Reverse Representation Problem
Peter F. Faul, Zurab Janelideze, Gideo Joubert
Cayley's theorem tells us that all groups occur as subgroups of the group of automorphisms over some set . In this paper we consider a `sort-of' converse to this qu…