Incorporating trivial rescaling/relabeling reductions
Develop a reduction or homomorphism framework that captures trivial equivalences induced by rescaling and relabeling of payoffs (such as the equivalence of 3LIN2 and 3LIN2(1,1)) within the algebraic theory of valued PCSPs.
References
There are however many basic questions and theory-building tasks left open already for finite-domain valued PCSPs: to incorporate the trivial reduction as in e.g. \cref{ex:crips-vs-valued}; to characterize gadget reductions (or versions of definability) in terms of polymorphisms or plurimorphisms; to characterize plurimorphism valued minions of templates; to clarify whether plurimorphisms are necessary to determine computational complexity or enough information is provided already by polymorphisms; to develop methods for proving nonexistence of homomorphisms; to revisit the valued CSP dichotomy without fixed threshold and Raghavendra's result on unique games hardness of approximation for all MaxCSPs; among others. An interesting special case for a full complexity classification is the valued non-promise CSPs with fixed threshold.