[Help-glpk] RE: Help-glpk Digest, Vol 22, Issue 12

[Q Wu]

Hi all,
I'm new to learn GLPK to solve LP problem, I have a simple model for Map 
Coloring problem as below, but when I tried to solve it, I got the following 
parse error at line 12#: argument for abs has invalid type. I'm very 
confused with this error.

And, I'm also wondering why strict inequality is not allowed in the model. 
Can anyone give some explanation? Thanks for any input in advance.

Rich Wu
#----Start------
set Country 'Country List';
param Adjacent 'Adjacent Maps' {Country, Country} logical;
var ColorAmount, integer, >= 1;
var CountryColor{Country} integer >=1;
#Objective
minimize ObjColorAmount: ColorAmount;
#Subject to
#Constraints
FirstCountryLim 'First Country Color Limit':
   CountryColor['c1'] = 1;
AdjacentLim 'Adjacent Limit' {ct1 in Country, ct2 in Country:ct1<>ct2 && 
Adjacent[ct1,ct2]=1}:
   abs(CountryColor[ct1]-(CountryColor[ct2]))>=1;
CountryNumber 'Country Number Limit' {c in Country}:
   CountryColor[c]<=ColorAmount;
display CountryColor;
#data
data;
set Country:=c1,c2,c3,c4,c5,c6,c7,c8,c9,c10,c11,c12,c13,c14,c15,c16,c17,c18;
param Adjacent default 0 (tr) :
   c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 c11 c12 c13 c14 c15 c16 c17 c18 :=
c1 0 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0
c2 1 0 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0
c3 0 1 0 1 1 0 0 0 1 0 0 0 0 0 0 0 0 1
c4 0 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0
c5 0 0 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1
c6 0 0 0 1 1 0 0 0 0 0 0 0 0 0 1 1 0 0
c7 1 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0
c8 1 1 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0
c9 0 1 1 0 0 0 0 1 0 1 1 0 0 0 0 0 0 1
c10 0 0 0 0 0 0 0 0 1 0 1 1 0 0 1 0 0 0
c11 0 0 0 0 0 0 1 1 1 1 0 1 0 1 0 0 0 0
c12 0 0 0 0 0 0 0 0 0 1 1 0 1 1 1 0 0 0
c13 0 0 0 0 0 0 0 0 0 0 0 1 0 1 1 1 1 0
c14 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 1 0
c15 0 0 0 0 1 1 0 0 1 1 0 1 1 0 0 1 1 0
c16 0 0 0 0 1 1 0 0 0 0 0 0 1 0 1 0 1 0
c17 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0
c18 0 0 1 0 1 0 0 0 1 0 0 0 0 0 1 0 0 0 ;
end;
#----end-----

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