TY - JOUR
TI - Impossibility theorems and the universal algebraic toolkit
DO - https://doi.org/doi:10.7282/T35M67QF
PY - 2015
AB - In this dissertation, we elucidate a close connection between the theory of Evaluation Aggregation, and a subfield of universal algebra, that was recently applied to investigate constraint satisfaction problems. Our connection yields a full classification of non-binary evaluations into possibility and impossibility domains both under the idempotent and the supportive conditions. Prior to the current result E. Dokow and R. Holzman nearly classified non-binary evaluations in the supportive case, by combinatorial means. The algebraic approach gives us new insights to the easier binary case as well, which had been fully classified by the above authors. We give a classification theorem for the majoritarian aggregator and show how Sen's well known theorem follows from it. Our algebraic view lets us put forth a suggestion about a strengthening of the non-dictatorship criterion, that helps us avoid "outliers'' like the affine subspace. Finally, we give upper bounds on the complexity of deciding if a domain is impossible or not (to our best knowledge no finite time bounds were given earlier).
KW - Computer Science
KW - Algebra
LA - eng
ER -