most recent 30 from http://mathoverflow.net 2013-05-24T13:45:10Z http://mathoverflow.net/feeds/question/68527 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/68527/a-name-for-pde-systems-which-are-neither-under-nor-overdetermined mathphysicist 2011-06-22T15:45:59Z 2011-06-22T18:53:01Z

<p>The concepts of <a href="http://eom.springer.de/O/o070660.htm" rel="nofollow">overdetermined</a> and <a href="http://eom.springer.de/u/u095150.htm" rel="nofollow">underdetermined</a> PDE systems are well known. However, all sources I have so far looked into appear to avoid giving any name to PDE systems which are <em>neither</em> overdetermined <em>nor</em> underdetermined. Is there any reasonably commonly used name for such PDE systems? If possible, please provide the references where the name from your answer is used.</p> <p><strong>EDIT:</strong> It was suggested by Igor Khavkine and Robert Bryant that one should consider <em>formally integrable</em> systems (which are neither over- nor underdetermined and have no nontrivial compatibility conditions). I like the idea but in my case this term would appear within the discussion of systems which are <em>completely integrable</em> (via the inverse scattering transform), and this might confuse the non-expert readers. Is there any sensible way out of this conundrum?</p> <p>Thanks in advance!</p>

http://mathoverflow.net/questions/68527/a-name-for-pde-systems-which-are-neither-under-nor-overdetermined/68531#68531 Ben McKay 2011-06-22T16:12:56Z 2011-06-22T16:12:56Z

<p>determined: Bryant et. al, Exterior Differential Systems, p. 189</p>