MarriageTheoremのこと

_ プレプリント確認状況：arXiv:math 9月13日分まで、arXiv:quant-ph 5月31日分まで、IACR ePrint：2012/064まで

_ さっき見つけた論文：Isomorphism versus commensurability for a class of finitely presented groups（Goulnara Arzhantseva, Jean-Francois Lafont, Ashot Minasyan, arXiv:1109.2225）

We construct a class of finitely presented groups where the isomorphism problem is solvable but the commensurability problem is unsolvable. Conversely, we construct a class of finitely presented groups within which the commensurability problem is solvable but the isomorphism problem is unsolvable. These are first examples of such a contrastive complexity behaviour with respect to the isomorphism problem.