In representation theory, there is a well-known notion of a wild classification problem (such problems have been discussed often on this forum, for example, [here][1]). In logic, there is a notion of an [undecidable problem][2]. > Is there a theorem which says that there is something undecidable about a wild classification problem? A reference where such issues are discussed would be very helpful. [1]: http://mathoverflow.net/questions/10481/when-is-a-classification-problem-wild/10484#10484 [2]: http://en.wikipedia.org/wiki/Undecidable_problem