[gecode-users] inforation on count constraints

[Kish Shen]

Hi,

I am trying to figure out if some of the versions of the count 
constraints corresponds to constraints in other places (e.g. the global 
constraint catalog, in other constraint systems, or in papers).
One of the count variants maps to the count constraint of the global 
constraint catalog (and SICStus), while another maps to (one version) of 
the global cardinality constraint. However, I was not able to determine 
if the other versions of count have any equivalent to constraints 
defined elsewhere, can anyone help by pointing me to any equivalent 
constraints that might be defined elsewhere for the following (these 
descriptions are based on the ones in the MPG):


count(home, x, c, IRT_EQ, z):

where x is an array of integer variables and c is an array of integers 
of the same array size as x, and z is an integer variable (or value).

which constrains z to how often xi = cl.


count(home, x, y)

where x and y are integer variable arrays.

which constraints the number of variables in x that are equal to a value 
j is yj.

This seems to be a restricted version of the global cardinality 
constraint. Is the reason for providing this more restricted form 
because this restriction allows for a more efficient implementation of 
the constraint?


On a slightly different topic, in the MPG description of the count 
constraints, there is a reference to

count(home, x IntSet(0,1), IntSet(0,n))

which seems to be an example of using

count(home, x, d, c)

where x is an array of integer variables, d is an integer set, and c an 
array of integer values -- but the last argument (IntSet(0,n)) is also 
an integer set. I also cannot find the description of count with two 
IntSet in the reference documentation (in doc-latest, I assume for 
3.5.0?) Am I missing something?

Thanks in advance for any information!

Kish

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