tag:blogger.com,1999:blog-8781383461061929571.post2876279322492138463..comments2024-03-14T09:08:19.035-04:00Comments on OR in an OB World: Indicator Implies RelationPaul A. Rubinhttp://www.blogger.com/profile/05801891157261357482noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-8781383461061929571.post-78189602937317067252013-11-29T10:55:29.198-05:002013-11-29T10:55:29.198-05:00What you wrote looks incorrect. Z is subscripted b...What you wrote looks incorrect. Z is subscripted by i and k but not j, so the condition T_k in [S_ik, S_jk] is tested for what value(s) of j?Paul A. Rubinhttps://www.blogger.com/profile/05801891157261357482noreply@blogger.comtag:blogger.com,1999:blog-8781383461061929571.post-44228082144577798882013-11-21T05:36:46.993-05:002013-11-21T05:36:46.993-05:00and Zik equql to 0 else and Zik equql to 0 else Anonymoushttps://www.blogger.com/profile/17382435723185989192noreply@blogger.comtag:blogger.com,1999:blog-8781383461061929571.post-90223395926035613262013-11-21T05:35:36.733-05:002013-11-21T05:35:36.733-05:00Hello,
i have a decision variable Zik equal to 1 i...Hello,<br />i have a decision variable Zik equal to 1 if a given parameter Tk is in [sik,sjk] were sik and sjk are decision variable please how model that,thank for advance for the reply Anonymoushttps://www.blogger.com/profile/17382435723185989192noreply@blogger.comtag:blogger.com,1999:blog-8781383461061929571.post-88262809127335192302013-11-20T21:21:41.785-05:002013-11-20T21:21:41.785-05:00a) Not exactly. If you are trying to model $y=1$ i...a) Not exactly. If you are trying to model $y=1$ if and only if $f(x)\gt 0$, then you want $f(x)\le 0$, not $f(x)\le 1$, when $y=0$. Also, you need to remember that $L$ and $U$ are the bounds for $f$, not $f-1$, and adjust accordingly.<br /><br />b) Yes, you need two binary variables to distinguish among three cases ($f$ positive, zero or negative).Paul A. Rubinhttps://www.blogger.com/profile/05801891157261357482noreply@blogger.comtag:blogger.com,1999:blog-8781383461061929571.post-66226868299270813992013-11-18T21:00:19.788-05:002013-11-18T21:00:19.788-05:00you state in the parting note that if f(x) is know...you state in the parting note that if f(x) is known to be integer-valued then f(x)>0 equates to f(x)>=1, f(x)<0 equates to f(x)<=-1, and f(x)<>0 is the disjunction of them. So:<br />a) when you state that "f(x)>0 equates to f(x)>=1" you mean that one should combine f(x)-1>=L(1-y) with f(x)-1<=Uy ?<br />b) when you state that "f(x)<>0 is the disjunction of the two previous cases" you mean that one must add an extra binary variable in order to model the condition that either the former or the latter case is true (but not both) ?Toupeira Mestrehttps://www.blogger.com/profile/10406051542136264564noreply@blogger.comtag:blogger.com,1999:blog-8781383461061929571.post-20786283083369023222013-11-18T20:59:13.411-05:002013-11-18T20:59:13.411-05:00This comment has been removed by the author.Toupeira Mestrehttps://www.blogger.com/profile/10406051542136264564noreply@blogger.com