For example:  Procedures for equitable division and exact division work equally well for cakes and for chores, since they guarantee equal values. An example is the Austin moving-knife procedure, which guarantees each partner a piece that he values as exactly 1/"n" of the total. The definition of envy-freeness in chore-cutting is the mirror-image of its definition in cake-cutting: each partner formula_1 should receive a piece formula_2 that is worth, according to his own personal disutility function, at most as much as any other piece:  For two partners, divide and choose produces an envy-free chore-cutting. However, for three or more partners, the situation is much more complicated. The main difficulty is in the "trimming" – the action of trimming a piece to make it equal to another piece (as done e.g. in the Selfridge–Conway protocol). This action cannot be easily translated to the chore-cutting scenario. Reza Oskui was the first who suggested a chore-cutting procedure for three partners. His work was never formally published; It is described in  pages 73–75. It is similar to the Selfridge–Conway protocol, but more complicated: it requires 9 cuts instead of 5 cuts. Below, the partners are called Alice, Bob and Carl. Step one. Alice cuts the chore to three pieces equal in her eyes (this is also the first step in the Selfidge-conway protocol). Bob and Carl specify their smallest piece. The easy case is that they disagree, since then we can give each partner a smallest piece and we are done. The hard case is that they agree. Let's call the piece, that both Bob and Carl view as smallest, X1, and the other two pieces, X2 and X3. Step two. Ask Bob and Carl to mark, on each of the pieces X2 and X3, where the piece has to be cut in order to make it equal to X1. We consider several cases. "Case 1." Bob's trims are weaker. I.e, if Bob trims X2 to X2' and X3 to X3', such that both X2' and X3' are for him as small as X1, then Carl thinks X1 is still a smallest piece – weakly smaller than X2' and X3'. Then, the following partial division is envy-free: Now we have to divide the trimmings E2 and E3.