[gecode-users] Difference between minus_r and nq

[mehdi m]

Hi,
I read and what i conclude (correct me please if i'm wrong) is that the two methods are equivalents in the case where the iterator represent only one value so minus_r will behave as an "nq" since it will remove only one value as "nq" do it !
Also, what i didn't notice is the difference in the case of "gq", for example :
x0 = {1,2,3,4,5}
If the iterator r represent the value {1,2,3}, so GECODE_ME_CHECK(x0.minus_r(home, r)); will remove these values from x0.And if i post :GECODE_ME_CHECK(x0.gq(home, 4)); in this case the value {1,2,3} are also removed from x0.
So, what is here the difference since the two methods remove the whole values {1,2,3} ?
Thanks.

From: cschulte at kth.se
To: medistif at hotmail.fr; users at gecode.org
Subject: RE: [gecode-users] Difference between minus_r and nq
Date: Tue, 10 Nov 2015 21:08:44 +0100

Hi, No, not all. For the details please read chapter 25 in MPG, it has the full story! The difference (in short) is that nq removes a single integer value, whereas minus_r removes a whole set of values represented by a range iterator. As said, please check MPG. Christian --Christian Schulte, www.gecode.org/~schulte Professor of Computer Science, KTH, cschulte at kth.seExpert Researcher, SICS, cschulte at sics.se From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf Of mehdi m
Sent: Tuesday, November 10, 2015 08:36 PM
To: users at gecode.org
Subject: [gecode-users] Difference between minus_r and nq Hi everyone, In the propagator implementation are the two following methods to remove values from domains equivalents ? - method 1 :Int::ViewRanges<Int::IntView> r(x1);GECODE_ME_CHECK(x0.minus_r(home, r)); - method 2GECODE_ME_CHECK(x0.nq(home, val)); Or there is any difference ? I see that the first one takes a ViewRange and the second can takes an Int directly but what about correctness and efficiency of pruning ? Thanks. 		 	   		  
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