Subsets of variables

GAMS
1

Hello everyone! I have a problem with sets and subsets definitions in a MIP formulation. I have 2 025; the firsts 225 are continue variables and the rest are binary variables.

Because of this I write:

k variables of the instance /k1k2025/
l(k) binary variables(0 <= x <= 1) /k226k2025/

And then I write:

VARIABLES
z objetive
x(k) variables;

BINARY VARIABLES
x(l) variables binarias;

But gams give me: Error 184 - Domain list redefined

How I can fix this?

the complete code that I used is the following:

$CALL GDXXRW 10teams.xlsx @teams.txt
$Title 10teams_ca

SETS
i filas matriz A /i1i95/
j filas matriz M /j1j135/
k variables de la instania /k1k2025/
l(k) subconjunto de variables binarys (0 <= x <= 1) /k226k2025/
m1(k) subconjunto de variables continuas FX=1 /k1, k51, k105, k165, k225/
m2(k) subconjunto de variables continuas FX=0;

m2(k) = (not l(k)) - m1(k);

PARAMETERS
A(i,k) matriz A
M(j,k) matriz M
b(i) vector b
g(j) vector g
c(k) vector de costos;

$GDXIN 10teams.gdx
$load A
$load M
$load b
$load g
$load c
$GDXIN

VARIABLES
z funcion objetivo
x(k) variables;

BINARY VARIABLES
x(l) variables binarias;


EQUATIONS
fobj funcion objetivo z
res1 restriccion 1
res2 restriccion 2;

fobj… z =e= sum(k,c(k)*x(k));
res1(i)… sum(k,A(i,k)*x(k)) =l= b(i);
res2(j)… sum(k,M(j,k)*x(k)) =e= g(j);
x.fx(m1) = 1;
x.fx(m2) = 0;

Model Centro /all/;

option mip=coincbc,rmip=coincbc;
solve Centro USING MIP MINIMIZING z;

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2

Fabián
Where are x(l) on your model?
You can substitute x(l) for another name: xx(l).
Why do you want the binaries a subset of the continuous variables?

Regards

Fabián Mancilla escreveu:

Hello everyone! I have a problem with sets and subsets definitions in a MIP formulation. I have 2 025; the firsts 225 are continue variables and the rest are binary variables.
Because of this I write:
k variables of the instance /k1*k2025/
l(k) binary variables(0
And then I write:

VARIABLES z objetive
x(k) variables;

BINARY VARIABLES
x(l) variables binarias;

But gams give me: Error 184 - Domain list redefined

How I can fix this?

the complete code that I used is the following:
$CALL GDXXRW 10teams.xlsx @teams.txt
$Title 10teams_ca

SETS
i filas matriz A /i1i95/
j filas matriz M /j1j135/
k variables de la instania /k1*k2025/
l(k) subconjunto de variables binarys (0 m1(k) subconjunto de variables continuas FX=1 /k1, k51, k105, k165, k225/
m2(k) subconjunto de variables continuas FX=0;

m2(k) = (not l(k)) - m1(k);

PARAMETERS
A(i,k) matriz A
M(j,k) matriz M
b(i) vector b
g(j) vector g
c(k) vector de costos;

$GDXIN 10teams.gdx
$load A
$load M
$load b
$load g
$load c
$GDXIN

VARIABLES
z funcion objetivo
x(k) variables;

BINARY VARIABLES
x(l) variables binarias;

EQUATIONS
fobj funcion objetivo z
res1 restriccion 1
res2 restriccion 2;

fobj… z =e= sum(k,c(k)*x(k));
res1(i)… sum(k,A(i,k)*x(k)) =l= b(i);
res2(j)… sum(k,M(j,k)*x(k)) =e= g(j);
x.fx(m1) = 1;
x.fx(m2) = 0;

Model Centro /all/;

option mip=coincbc,rmip=coincbc;
solve Centro USING MIP MINIMIZING z;

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3

Hi
I think the easiest way is to seperate the variables :

k1 continious variables /1225/
k2 binary variables /2252025/
;
Variables
x1(k1)
x2(k2)
;
BinaryVariables
x2
;

2010/12/22 Fabián Mancilla

Hello everyone! I have a problem with sets and subsets definitions in a MIP formulation. I have 2 025; the firsts 225 are continue variables and the rest are binary variables.

Because of this I write:

k variables of the instance /k1k2025/
l(k) binary variables(0 <= x <= 1) /k226k2025/

And then I write:

VARIABLES
z objetive
x(k) variables;

BINARY VARIABLES
x(l) variables binarias;

But gams give me: Error 184 - Domain list redefined

How I can fix this?

the complete code that I used is the following:

$CALL GDXXRW 10teams.xlsx @teams.txt
$Title 10teams_ca

SETS
i filas matriz A /i1i95/
j filas matriz M /j1j135/
k variables de la instania /k1k2025/
l(k) subconjunto de variables binarys (0 <= x <= 1) /k226k2025/
m1(k) subconjunto de variables continuas FX=1 /k1, k51, k105, k165, k225/
m2(k) subconjunto de variables continuas FX=0;

m2(k) = (not l(k)) - m1(k);

PARAMETERS
A(i,k) matriz A
M(j,k) matriz M
b(i) vector b
g(j) vector g
c(k) vector de costos;

$GDXIN 10teams.gdx
$load A
$load M
$load b
$load g
$load c
$GDXIN

VARIABLES
z funcion objetivo
x(k) variables;

BINARY VARIABLES
x(l) variables binarias;


EQUATIONS
fobj funcion objetivo z
res1 restriccion 1
res2 restriccion 2;

fobj… z =e= sum(k,c(k)*x(k));
res1(i)… sum(k,A(i,k)*x(k)) =l= b(i);
res2(j)… sum(k,M(j,k)*x(k)) =e= g(j);
x.fx(m1) = 1;
x.fx(m2) = 0;

Model Centro /all/;

option mip=coincbc,rmip=coincbc;
solve Centro USING MIP MINIMIZING z;

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Babak Saleck Pay
Group of Industrial Engineering
M.Sc
Operations Research
University of Tehran
Tehran,Iran

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4

Edson and Babak:

Well, I have a lot data of a LP problem in a GDX file. But I need consider some like binary and since the coeficients of the matrix “A” & “M” depend of the index “k” (System of the form Ax<=b; Mx=g), I define the subset “I” of “k” and I try to declaring “x(I)” binary variables. Thus the formulation of the equations is more easy (I think). However this seem not possible.

Regars and thanks

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5

Fabian,

Did you manage to solve this problem, without defining a separate set of variables? I have encountered a similar issue and it will be quite a pain to have to split my ‘x’ vector into continuous, integer and binary components!

Jonathan

On Thursday, December 30, 2010 4:11:02 PM UTC+13, Fabián Mancilla wrote:

Edson and Babak:

Well, I have a lot data of a LP problem in a GDX file. But I need consider some like binary and since the coeficients of the matrix “A” & “M” depend of the index “k” (System of the form Ax<=b; Mx=g), I define the subset “I” of “k” and I try to declaring “x(I)” binary variables. Thus the formulation of the equations is more easy (I think). However this seem not possible.

Regars and thanks

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