%0 Journal Article %T Sortable elements and Cambrian lattices %A Nathan Reading %J Mathematics %D 2005 %I arXiv %X We show that the Coxeter-sortable elements in a finite Coxeter group W are the minimal congruence-class representatives of a lattice congruence of the weak order on W. We identify this congruence as the Cambrian congruence on W, so that the Cambrian lattice is the weak order on Coxeter-sortable elements. These results exhibit W-Catalan combinatorics arising in the context of the lattice theory of the weak order on W. %U http://arxiv.org/abs/math/0512339v1