[gecode-users] Constraints on "wave" form

[Richard Portelli]

Sorry it's RIchard again,
you meant :

y[i] = (x[i] < y[i])

or

y[i] = (x[i] < x[i-1])



2014-06-12 12:48 GMT+02:00 Richard Portelli <richard.portell at gmail.com>:

> Sorry it's RIchard again,
> you meant :
>
>
> 2014-06-12 11:50 GMT+02:00 Mikael Zayenz Lagerkvist <zayenz at gmail.com>:
>
>> Richard Portelli skrev 12/06/14 10:32:
>>
>>  Hello Christian,
>>> I would like to know if there is an easy way to implement a special
>>> constraint.
>>> I have an array with 10 numbers.
>>> My constraint would be : if you plot the array values in function of the
>>> index,  you should have a wave aspect /\.
>>> For example with 10 numbers
>>>
>>> 1 3 5 9 11 7 6 5 4 2 0 (increasing then decreasing) There is no
>>> importance at witch index there is the inflexion point.
>>>
>>> Would you have an idea how to implement that in a clean way?
>>>
>>>
>> For reference, this is similar to the inflexion constraint (
>> http://www.emn.fr/z-info/sdemasse/gccat/Cinflexion.html) with the number
>> of inflexions set to 1 (assuming that valleys are also ok).
>>
>> The simplest way in my opinion to model this constraint would be the
>> following.
>>
>>   Assume the sequence of numbers is called x and has n entries.
>>   Define a new boolean array of variables y with n-1 values.
>>   For each place i in y, add the constraint
>>     y[i] = (x[i] < y[i])
>>   (that is, reified ordering).
>>   On the y variables, add the constraint regular(y, 1*0*)
>>
>> The ordering constraint and the regular expression can be modified to
>> suit your particular needs.
>>
>> Cheers,
>> Mikael
>>
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>
>
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