sci.op-research

Dnia Sat, 22 Mar 2008 09:18:27 +0100
Wit Jakuczun napisa=C5=82(a):

> Dnia Fri, 21 Mar 2008 15:35:08 -0700 (PDT)
> "xgeneral57@gmail.com" napisa=C5=82(a):
>=20
> >=20
> > if x(i)=3Dxp(i)-xn(i) where xp(i) and xn(i) are two nonnegative slack
> > variables, then to enforce exactly one of them to be zero I would
> > need to maximize
> > |x(i)|=3Dz=3Dxp(i)+xn(i).
> > But this is not the case for me.
> You can also bind with them two binary variables: xpb(i) and xnb(i)
> such that:
> xp(i) <=3D xpb(i)*UB
> xn(i) <=3D xnb(i)*UB
>=20
> By adding constraint: xpb(i) + xnb(i) =3D 1 you will get exactly one
> of them 0 without maximizing |x(i)|.=20
>=20
Having: xpb(i) + xnb(i) <=3D 1 you could use the variables to
estimate whether x(i) is zero.=20

Best regards
--=20
[ Wit Jakuczun ]
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