Open problems with at most one unknown solution and some known solutions - MathOverflow most recent 30 from http://mathoverflow.net 2013-06-20T08:33:22Z http://mathoverflow.net/feeds/question/101758 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/101758/open-problems-with-at-most-one-unknown-solution-and-some-known-solutions Open problems with at most one unknown solution and some known solutions joro 2012-07-09T09:39:03Z 2012-07-09T09:39:03Z <blockquote> <p>What are examples of open problems with at most one unknown solution and some known solutions?</p> </blockquote> <p>Some examples:</p> <p>There is at most one more <a href="https://en.wikipedia.org/wiki/Idoneal_number" rel="nofollow">Idoneal number</a>.</p> <p><a href="http://math.ucalgary.ca/~ramollin/cn2frqfrdt.pdf" rel="nofollow">CLASS NUMBER TWO FOR REAL QUADRATIC FIELDS OF RICHAUD-DEGERT TYPE</a>: The following are equivalent (a) \$h_\Delta=2\$ (b) \$\Delta\$ s one of the following values, with one GRH-ruled-out exception: {85, 165, 221, 285, ...</p> <p>Trying the make the question well defined the problems shouldn't be artificially constructed.</p> <p>Preferably the missing solution shouldn't be ruled out by some plausible conjecture.</p>