{"action":"created","issue":{"url":"https://api.github.com/repos/Macaulay2/M2/issues/294","labels_url":"https://api.github.com/repos/Macaulay2/M2/issues/294/labels{/name}","comments_url":"https://api.github.com/repos/Macaulay2/M2/issues/294/comments","events_url":"https://api.github.com/repos/Macaulay2/M2/issues/294/events","html_url":"https://github.com/Macaulay2/M2/issues/294","id":85756276,"number":294,"title":"Logic for deciding if a GB algorithm applies is incomplete","user":{"login":"mikestillman","id":102215,"avatar_url":"https://avatars.githubusercontent.com/u/102215?v=3","gravatar_id":"","url":"https://api.github.com/users/mikestillman","html_url":"https://github.com/mikestillman","followers_url":"https://api.github.com/users/mikestillman/followers","following_url":"https://api.github.com/users/mikestillman/following{/other_user}","gists_url":"https://api.github.com/users/mikestillman/gists{/gist_id}","starred_url":"https://api.github.com/users/mikestillman/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mikestillman/subscriptions","organizations_url":"https://api.github.com/users/mikestillman/orgs","repos_url":"https://api.github.com/users/mikestillman/repos","events_url":"https://api.github.com/users/mikestillman/events{/privacy}","received_events_url":"https://api.github.com/users/mikestillman/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-06-06T14:16:07Z","updated_at":"2015-06-06T14:23:53Z","closed_at":null,"body":"In m2/gb.m2, we need to make the following tests for correctness:\r\n\r\nIf the base ring is ZZ (ultimately), then the only allowed algorithm is “Inhomogeneous”\r\nIf the monomial order is a local order (even in a coefficient ring), then the algorithm must be “Inhomogeneous”\r\nBUT: if both of these hold, then a “not implemented yet” error should be given.\r\n\r\n(the “Inhomogeneous\" algorithm is the only one to be able to handle the base being ZZ, or having local rings).  Actually, the GB routine itself can handle it, but my minimalization algorithm isn’t designed for that case (yet).\r\n\r\nI can change this in the engine, but the front end is probably where these checks should be."},"comment":{"url":"https://api.github.com/repos/Macaulay2/M2/issues/comments/109583828","html_url":"https://github.com/Macaulay2/M2/issues/294#issuecomment-109583828","issue_url":"https://api.github.com/repos/Macaulay2/M2/issues/294","id":109583828,"user":{"login":"mikestillman","id":102215,"avatar_url":"https://avatars.githubusercontent.com/u/102215?v=3","gravatar_id":"","url":"https://api.github.com/users/mikestillman","html_url":"https://github.com/mikestillman","followers_url":"https://api.github.com/users/mikestillman/followers","following_url":"https://api.github.com/users/mikestillman/following{/other_user}","gists_url":"https://api.github.com/users/mikestillman/gists{/gist_id}","starred_url":"https://api.github.com/users/mikestillman/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mikestillman/subscriptions","organizations_url":"https://api.github.com/users/mikestillman/orgs","repos_url":"https://api.github.com/users/mikestillman/repos","events_url":"https://api.github.com/users/mikestillman/events{/privacy}","received_events_url":"https://api.github.com/users/mikestillman/received_events","type":"User","site_admin":false},"created_at":"2015-06-06T14:23:53Z","updated_at":"2015-06-06T14:23:53Z","body":"Some examples:\r\n```\r\nA = ZZ/5[a,b,c,MonomialOrder=>RevLex,Global=>false]\r\nB = A[x,y,z] -- How do we tell that this has a local term order?  (monoid B).Options.Global is true\r\ngens gb matrix{{a*x, a-a^2}} -- works, as it should\r\n\r\nC = ZZ[d,e,f]\r\nI = ideal(3*d-2, 5*e-1)\r\ngens gb(I, Algorithm=>Homogeneous2)  -- should fail, and it does\r\ngens gb(ideal(3*d-2*e, 4*d-f), Algorithm=>Homogeneous2) -- should fail\r\ngens gb(ideal(a^2-b^2, a*b), Algorithm=>Homogeneous2) -- should fail too\r\n\r\nD = ZZ[g,h,MonomialOrder=>RevLex,Global=>false]\r\ngens gb ideal(3*g,5*h) -- should fail? GB can be computed, but it hangs when trying to minimize it.\r\n```\r\n\r\n"}}