{"action":"created","issue":{"url":"https://api.github.com/repos/coin-or/Cbc/issues/81","repository_url":"https://api.github.com/repos/coin-or/Cbc","labels_url":"https://api.github.com/repos/coin-or/Cbc/issues/81/labels{/name}","comments_url":"https://api.github.com/repos/coin-or/Cbc/issues/81/comments","events_url":"https://api.github.com/repos/coin-or/Cbc/issues/81/events","html_url":"https://github.com/coin-or/Cbc/issues/81","id":371605458,"node_id":"MDU6SXNzdWUzNzE2MDU0NTg=","number":81,"title":"[Trac #123] CBC.exe produces an \"optimal\" IP solution that violates a BigM constraint - a scaling problem?","user":{"login":"s-c-e","id":11558962,"node_id":"MDQ6VXNlcjExNTU4OTYy","avatar_url":"https://avatars3.githubusercontent.com/u/11558962?v=4","gravatar_id":"","url":"https://api.github.com/users/s-c-e","html_url":"https://github.com/s-c-e","followers_url":"https://api.github.com/users/s-c-e/followers","following_url":"https://api.github.com/users/s-c-e/following{/other_user}","gists_url":"https://api.github.com/users/s-c-e/gists{/gist_id}","starred_url":"https://api.github.com/users/s-c-e/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/s-c-e/subscriptions","organizations_url":"https://api.github.com/users/s-c-e/orgs","repos_url":"https://api.github.com/users/s-c-e/repos","events_url":"https://api.github.com/users/s-c-e/events{/privacy}","received_events_url":"https://api.github.com/users/s-c-e/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2018-10-18T16:10:29Z","updated_at":"2018-10-18T21:30:11Z","closed_at":null,"author_association":"NONE","body":"\r\n![image](https://user-images.githubusercontent.com/11558962/47168350-47842400-d2c6-11e8-8ff1-17dd08c665e4.png)\r\n\r\nAttachment: https://github.com/s-c-e/cbc-trac-migration-attachments/blob/master/trac-ticket-123.zip\r\n\r\nAn OpenSolver user has sent me a spreadsheet that has some large BigM values. Solving with these large values leads CBC.exe to return a solution reported as optimal that violates at least 1 constraint. Reducing the BigM by a factor of 100 produces a new, now feasible solution.\r\n\r\nI have attached (1) Sue's Model - CBC gives wrong answer.txt My summary of the issue (2) model2.lp and modelsolution2.txt Original Input and solution showing the violated constraint (3) model.lp and modelsolution.txt Modified input (smaller BigM) and a new solution that does not violate the modified constraint\r\n\r\nPlease contact me if you need any more information.\r\n\r\nThanks, Andrew"},"comment":{"url":"https://api.github.com/repos/coin-or/Cbc/issues/comments/431170777","html_url":"https://github.com/coin-or/Cbc/issues/81#issuecomment-431170777","issue_url":"https://api.github.com/repos/coin-or/Cbc/issues/81","id":431170777,"node_id":"MDEyOklzc3VlQ29tbWVudDQzMTE3MDc3Nw==","user":{"login":"s-c-e","id":11558962,"node_id":"MDQ6VXNlcjExNTU4OTYy","avatar_url":"https://avatars3.githubusercontent.com/u/11558962?v=4","gravatar_id":"","url":"https://api.github.com/users/s-c-e","html_url":"https://github.com/s-c-e","followers_url":"https://api.github.com/users/s-c-e/followers","following_url":"https://api.github.com/users/s-c-e/following{/other_user}","gists_url":"https://api.github.com/users/s-c-e/gists{/gist_id}","starred_url":"https://api.github.com/users/s-c-e/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/s-c-e/subscriptions","organizations_url":"https://api.github.com/users/s-c-e/orgs","repos_url":"https://api.github.com/users/s-c-e/repos","events_url":"https://api.github.com/users/s-c-e/events{/privacy}","received_events_url":"https://api.github.com/users/s-c-e/received_events","type":"User","site_admin":false},"created_at":"2018-10-18T21:30:11Z","updated_at":"2018-10-18T21:30:11Z","author_association":"NONE","body":"I've executed both ```model.lp``` and ```model2.lp``` and I get the same solutions - with objective = 10.0. Log files are respectively linked here: \r\nhttps://gist.github.com/s-c-e/cbc31a29eaff767ca8ad570c5abb9cdf\r\nhttps://gist.github.com/s-c-e/b0f9baea014ca0ceb8026df42734a882"}}
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