{"action":"created","issue":{"url":"https://api.github.com/repos/sympy/sympy/issues/9815","repository_url":"https://api.github.com/repos/sympy/sympy","labels_url":"https://api.github.com/repos/sympy/sympy/issues/9815/labels{/name}","comments_url":"https://api.github.com/repos/sympy/sympy/issues/9815/comments","events_url":"https://api.github.com/repos/sympy/sympy/issues/9815/events","html_url":"https://github.com/sympy/sympy/issues/9815","id":100530939,"number":9815,"title":"Implement representation for arbitrarily indexed Unions and Intersections ","user":{"login":"hargup","id":2477788,"avatar_url":"https://avatars2.githubusercontent.com/u/2477788?v=4","gravatar_id":"","url":"https://api.github.com/users/hargup","html_url":"https://github.com/hargup","followers_url":"https://api.github.com/users/hargup/followers","following_url":"https://api.github.com/users/hargup/following{/other_user}","gists_url":"https://api.github.com/users/hargup/gists{/gist_id}","starred_url":"https://api.github.com/users/hargup/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hargup/subscriptions","organizations_url":"https://api.github.com/users/hargup/orgs","repos_url":"https://api.github.com/users/hargup/repos","events_url":"https://api.github.com/users/hargup/events{/privacy}","received_events_url":"https://api.github.com/users/hargup/received_events","type":"User","site_admin":false},"labels":[{"id":84627405,"url":"https://api.github.com/repos/sympy/sympy/labels/sets","name":"sets","color":"0000FF","default":false}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":10,"created_at":"2015-08-12T12:23:17Z","updated_at":"2018-03-17T16:25:06Z","closed_at":null,"author_association":"MEMBER","body":"At present SymPy cannot represent arbitrarily index Unions and intersection. In symbolic notation we need ![union](http://quicklatex.com/cache3/34/ql_32bcb1c766c59cfacf8c1ae865045534_l3.png) and ![intersection](http://quicklatex.com/cache3/01/ql_7fd273d7d061055326621fd5d4d44901_l3.png) where ![alpha](http://quicklatex.com/cache3/63/ql_1b9327312b7a89e41390c82ab91a2963_l3.png) is the indexing variable, ![I](http://quicklatex.com/cache3/d2/ql_6c9c97eaa68c70fa6daa0659890b4cd2_l3.png) is the index set and ![X_alpha](http://quicklatex.com/cache3/f5/ql_a92029191aa0a7458c3c785473de65f5_l3.png) forms a collection of sets indexed by ![alpha](http://quicklatex.com/cache3/63/ql_1b9327312b7a89e41390c82ab91a2963_l3.png).\n\nIf we allow a Set objects as input to union, then the above Union can be represented by, Intersections can be represented similarly.\n\n``` python\nUnion(ImageSet(Lambda(a, X(a)), I)\n```\n"},"comment":{"url":"https://api.github.com/repos/sympy/sympy/issues/comments/373932983","html_url":"https://github.com/sympy/sympy/issues/9815#issuecomment-373932983","issue_url":"https://api.github.com/repos/sympy/sympy/issues/9815","id":373932983,"user":{"login":"jksuom","id":6929119,"avatar_url":"https://avatars3.githubusercontent.com/u/6929119?v=4","gravatar_id":"","url":"https://api.github.com/users/jksuom","html_url":"https://github.com/jksuom","followers_url":"https://api.github.com/users/jksuom/followers","following_url":"https://api.github.com/users/jksuom/following{/other_user}","gists_url":"https://api.github.com/users/jksuom/gists{/gist_id}","starred_url":"https://api.github.com/users/jksuom/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jksuom/subscriptions","organizations_url":"https://api.github.com/users/jksuom/orgs","repos_url":"https://api.github.com/users/jksuom/repos","events_url":"https://api.github.com/users/jksuom/events{/privacy}","received_events_url":"https://api.github.com/users/jksuom/received_events","type":"User","site_admin":false},"created_at":"2018-03-17T16:25:06Z","updated_at":"2018-03-17T16:25:06Z","author_association":"MEMBER","body":"The FiniteSet case looks plausible to me, but a union of intervals can be returned as an Interval only if it happens to be one. In general, a BigUnion class with redefined `contains` (or `_contains`) should probably be defined."}}
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