  For any finite Coxeter group W, we introduce two new objects: its cutting
poset and its biHecke monoid. The cutting poset, constructed using a
generalization of the notion of blocks in permutation matrices, almost forms a
lattice on W. The construction of the biHecke monoid relies on the usual
combinatorial model for the 0-Hecke algebra H_0(W), that is, for the symmetric
group, the algebra (or monoid) generated by the elementary bubble sort
operators. The authors previously introduced the Hecke group algebra,
constructed as the algebra generated simultaneously by the bubble sort and
antisort operators, and described its representation theory. In this paper, we
consider instead the monoid generated by these operators. We prove that it
admits |W| simple and projective modules. In order to construct the simple
modules, we introduce for each w in W a combinatorial module T_w whose support
is the interval [1,w]_R in right weak order. This module yields an algebra,
whose representation theory generalizes that of the Hecke group algebra, with
the combinatorics of descents replaced by that of blocks and of the cutting
poset.
