most recent 30 from http://mathoverflow.net 2013-05-24T10:01:23Z http://mathoverflow.net/feeds/question/73153 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/73153/is-there-an-algorithm-for-computing-schur-multiplier Al Tal 2011-08-18T14:04:40Z 2011-08-18T14:30:44Z

<p>Suppose we are given group $G=\langle a_1,\ldots,a_n \mid R_1=1,\ldots R_m=1 \rangle$. Is there an algorithm which computes a finite presentation for the Schur multiplier, i.e. second homology group $K=H^2(G,\mathbb{Z})$? Can one at least solve a decision problem, whether $K$ is trivial or not?</p>

http://mathoverflow.net/questions/73153/is-there-an-algorithm-for-computing-schur-multiplier/73155#73155 Gjergji Zaimi 2011-08-18T14:30:44Z 2011-08-18T14:30:44Z

<p>It is proved in "Some embedding theorems and undecidability questions for groups" by C. Gordon, that there is no algorithm that computes a presentation for the Schur multiplier from a presentation of $G$, and moreover there is no algorithm for the deciding whether the Schur multiplier is trivial or not. Some other similar related results are proved, as well.</p>