Malcolm Ryan wote:
> On 03/06/2008, at 7:45 PM, Guido Tack wrote:
>
>> The problem is here: testing B.in(b) is linear time, so it's just as
>> expensive as finding a new b.
>
> Ah. Is there a way to iterate through the elements of B's domain in
> order in time proportional to the number of element
Hmm, I really don't think I understand your code well enough to do
this properly. I'm trying to implement a reified A < B < C operator,
but I'm really lost.
Malcolm
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On 03/06/2008, at 7:45 PM, Guido Tack wrote:
> Ok, great. If you need help with writing the propagator, or with
> interfacing it to Java, let us know! I'd start by looking at the
> propagate function of ReEqDom in gecode/int/rel/eq.icc for an
> example of a C++ reified propagator.
Eek. I
On 03/06/2008, at 7:45 PM, Guido Tack wrote:
> The problem is here: testing B.in(b) is linear time, so it's just as
> expensive as finding a new b.
Ah. Is there a way to iterate through the elements of B's domain in
order in time proportional to the number of elements?
Malcolm
Malcolm Ryan wrote:
> On 03/06/2008, at 6:40 PM, Guido Tack wrote:
>>
>>> If we kept the smallest value of b
>>> between propagations the amortised cost of the computation could be
>>> small.
>>
>> That wouldn't help, because you cannot start checking for values
>> starting from that previous smal
On 03/06/2008, at 6:40 PM, Guido Tack wrote:
>
>> If we kept the smallest value of b
>> between propagations the amortised cost of the computation could be
>> small.
>
> That wouldn't help, because you cannot start checking for values
> starting from that previous smallest value.
Why not? Most
Malcolm Ryan wrote:
> Hrm, it seems that the extensional version is going to be inordinately
> large. How hard would it be to write a propagator for this specific
> constraint X = (A < B < C)?
>
> If X is known, it can simply devolve into atomic constraints.
> If X is unknown, it would just need t
Hrm, it seems that the extensional version is going to be inordinately
large. How hard would it be to write a propagator for this specific
constraint X = (A < B < C)?
If X is known, it can simply devolve into atomic constraints.
If X is unknown, it would just need to check that there exists b
Malcolm Ryan wrote:
> On 02/06/2008, at 5:18 PM, Guido Tack wrote:
>>
>> Oh, I somehow didn't see that it's always ternary! In that case you
>> might really want to try the extensional constraint. Just implement
>> a generator that lists all allowed tuples.
>
> Nice idea, but really not viable.
On 02/06/2008, at 5:18 PM, Guido Tack wrote:
>
> Oh, I somehow didn't see that it's always ternary! In that case you
> might really want to try the extensional constraint. Just implement
> a generator that lists all allowed tuples.
Nice idea, but really not viable. In practice the domains ar
Malcolm Ryan wrote:
> What I need is a reified version of the pairwise rel(). Then I could
> say:
>
> a < c --> a < b < c
> b < a --> b < c < a
> c < b --> c < a < b
>
> Since there is no value of 'a' that satisfies c < a < b, it would have
> to deduce that b < c.
>
> Representing this as (c < a)
What I need is a reified version of the pairwise rel(). Then I could
say:
a < c --> a < b < c
b < a --> b < c < a
c < b --> c < a < b
Since there is no value of 'a' that satisfies c < a < b, it would have
to deduce that b < c.
Representing this as (c < a) and (a < b) is not good enough, as t
Malcolm Ryan wrote:
I want to make a constraint which represents the order of three values
around a ring.
Eg: if we have a,b,c \in {1,2,3,4} then I want to represent the
constraint:
clockwise(a,b,c) == (a < b < c) or (b < c < a) or (c < a < b)
I can construct this directly using BExprs, but t
I want to make a constraint which represents the order of three values
around a ring.
Eg: if we have a,b,c \in {1,2,3,4} then I want to represent the
constraint:
clockwise(a,b,c) == (a < b < c) or (b < c < a) or (c < a < b)
I can construct this directly using BExprs, but the use of 'or' mean
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