I've discovered that I can do what I want by posting BExprs anyway, and never have to create all those reified Booleans. Yay.
Malcolm On 10/03/2008, at 6:42 PM, Mikael Zayenz Lagerkvist wrote: > For all reified constraints that I can think of, instantiating the > "base" variables will also mean that the Boolean variable will get > instantiated. However, if you build more complicated expressions with > the Booleans and additional intermediate variables, then these might > not be instantiated. For example, think of the following constraint > system > IntVar x; > BoolVar IsA, IsB, Neither; > x = a <=> IsA; > x = b <=> IsB; > IsA \/ IsB \/ Neither; > The variable Neither will not be instantiated if x is instantiated to > a or b (it can be either true or false, the constraints are satisfied > either way). > > Cheers, > Mikael > > On Mon, Mar 10, 2008 at 5:05 AM, Malcolm Ryan <[EMAIL PROTECTED] > > wrote: >> If I use reification like this, do I have to write my search code so >> that it instantiates all the booleans as well as all the 'normal' >> variables? Or can I rely on the fact that once all the 'normal' >> variables are instantiated all the booleans should also be >> instantiated. >> >> Malcolm >> >> >> >> On 06/03/2008, at 4:15 PM, Christian Schulte wrote: >> >>> Use reification, that's clumsy but works. So, with minimodeling >>> support it >>> should be something like (~ reifies a linear relation, && is >>> conjunction, >>> imp is implication, and tt means that the statement must be true): >>> post(home, tt(imp(~(v1 == 2),~(v2 != 1) && ~(v3 != 3))); >>> or directly: >>> BoolVar b1(home,0,1), b2(home,0,1), b3(home,0,1), b23(home, >>> 0,1); >>> rel(home, v1, IRT_EQ, 2, b1); >>> rel(home, v2, IRT_NQ, 1, b2); >>> rel(home, v3, IRT_NQ, 3, b3); >>> rel(home, b2, BOT_AND, b3, b23); >>> rel(home, b1, BOT_IMP, b23, 1); >>> >>> Or check whether extensional constraints work for you. >>> >>> Christian >>> >>> -- >>> Christian Schulte, www.ict.kth.se/~cschulte/ >>> >>> >>> -----Original Message----- >>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On >>> Behalf >>> Of Debdeep Banerjee >>> Sent: Thursday, March 06, 2008 3:03 PM >>> To: [EMAIL PROTECTED] >>> Cc: [EMAIL PROTECTED] >>> Subject: [gecode-users] If then type constraints >>> >>> Hi, >>> How do I model if-then style constraints ? What I want to do is post >>> constraints if a variable is assigned a particular value. For >>> example >>> say I have variable set V { v1, v2, v3} and each of them has the >>> domain >>> {1,2,3}. what I want to achieve is >>> if v1== 2 then >>> v2 !=1 /\ v3 !=3 >>> >>> I know I can do this using a custom propagator, but is there any >>> other way ? >>> >>> With regards >>> Debdeep >>> >>> -- >>> Debdeep Banerjee >>> PhD Candidate >>> CSL/RSISE/NICTA >>> Australian National University >>> Email: [EMAIL PROTECTED] >>> Web:http://rsise.anu.edu.au/~banerjed >>> >>> >>> >>> _______________________________________________ >>> Gecode users mailing list >>> [EMAIL PROTECTED] >>> https://www.gecode.org/mailman/listinfo/gecode-users >>> >>> >>> _______________________________________________ >>> Gecode users mailing list >>> [EMAIL PROTECTED] >>> https://www.gecode.org/mailman/listinfo/gecode-users >> >> >> _______________________________________________ >> Gecode users mailing list >> [EMAIL PROTECTED] >> https://www.gecode.org/mailman/listinfo/gecode-users >> > > > > -- > Mikael Zayenz Lagerkvist, http://www.ict.kth.se/~zayenz/ _______________________________________________ Gecode users mailing list [EMAIL PROTECTED] https://www.gecode.org/mailman/listinfo/gecode-users
