Cohen, D., Creed, P., Jeavons, P., & Živný, S. (2011). An algebraic theory of complexity for valued constraints: Establishing a Galois connection. Springer.

Cohen, D., P. Creed, P. Jeavons, and S. Živný. An Algebraic Theory of Complexity for Valued Constraints: Establishing a Galois Connection. Springer, 2011.

Cohen, D., et al. An Algebraic Theory of Complexity for Valued Constraints: Establishing a Galois Connection. Springer, 2011.