question, until in 2009 Peterson and Su published a procedure for n partners. It is analogous to the Brams–Taylor procedure and uses the same idea of irrevocable advantage. Instead of trimming, they use adding from reserve. Dehghani et al.'s discrete and bounded procedure for any number of partners Peterson and Su gave a moving knife procedure for 4-person chore division. Dehghani et al. provided the first discrete and bounded envy-free protocol for chore division among any number of agents. Procedures for connected pieces The following procedures can be adapted to divide a bad cake with disconnected pieces: Robertson–Webb rotating-knife procedure Stromquist moving-knives procedure Simmons–Su protocols. Simmons originally developed a protocol for approximate envy-free cake-cutting with connected pieces, based on Sperner's lemma. Su showed, using a dual lemma, that a similar protocol can be used for approximate envy-free chore division. In particular, it shows that there always exists an envy-free chore division with connected pieces. Price-of-fairness Heydrich and van Stee calculate the price of fairness in chore division when the pieces have to be connected. Applications It may be possible to use chore division procedures to divide up the work and cost of reducing climate change among nations. Problems occur with morals and getting cooperation between nations. However, using chore division procedures reduces the need for a supra-national authority to partition and oversee work by those nations. Another use for chore division would be in the rental harmony problem. References See also Envy-free cake-cutting Bad (economics) Rental harmony Cake-cutting Fair division protocols