Multi-dimensional sets/mapping

[Rahul Sharma]

Hi,
I am looking for some reference on creating many-many mapping in a
set.
The text below is from the GAMS manual:
Consider a set whose elements are pairs: A = {(b; d); (a; c); (c; e)}.

set c "countries"
/ jamaica
haiti
guyana
brazil / ;

and the set of ports is
set p "ports"
/ kingston
s-domingo
georgetown
belem / ;

set ptoc(p, c) "port to country relationship"

/ kingston .jamaica
s-domingo .haiti
georgetown .guyana
belem .brazil /;
The dot between kingston and jamaica is used to create one such pair.

In AIMMS how do i associate the "." operation if i want to create
subsets and map them based on existing sets?

[Guido Diepen]

Hi,

you can do this by using parentheses around the combinations. Your example can be introduced as follows in AIMMS:

DECLARATION SECTION 

  SET:

     identifier :  Countries

     index      :  c

     definition :  data { jamaica , haiti , guyana , brazil } ;

  SET:

     identifier :  Ports

     index      :  p

     definition :  data { kingston , s-domingo , georgetown ,belem } ;

  SET:

     identifier :  PortToCountry

     subset of  :  (Ports,Countries)

     definition :  data { ( kingston, jamaica ), ( s-domingo, haiti ), ( georgetown, guyana ), ( belem, brazil ) } ;

ENDSECTION  ;

So instead of using the . in between, you just use ( ) around the combination.

Guido Diepen

AIMMS Specialist

[Rahul Sharma]

Thanks!!
I have another question to add, if i want to associate two or more
entries for ex:
Kingston. Jamaica,Haiti..Can I still use the syntax: data {(kingston,
(jamaica,haiti))}

[Guido Diepen]

Hi,

It is not possible with the syntax you stated, but each combination must be given explicitly, so

data {(kingston, jamaica) , (kingston, haiti) } 

Guido Diepen

AIMMS Specialist

[Rahul Sharma]

Thanks !! Helped me get clarified