The model is locally infeasible. However, feasible solutions may or may no...

2012fang

请问我用lingo15求解一下程序，出现The model is locally infeasible.  However, feasible solutions may or may not exist in other regions.  Consider invoking the global solver or the multistart feature.
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model:
sets:
teachers/1..3/;
students/1..5/:d;
places/p1 p2 p3/;
times/t1 t2/;
majors/m1 m2 m3/;
link1(students,teachers):a;
link2(teachers,times):b;
link3(teachers,majors):c;
link5(teachers,times,places):x;
link6(students,times,places):y;
endsets
[objective] max=@sum(places(p)sum(times(t)sum(teachers(l)sum(students(s)c(l,d(s))*x(l,t,p)*y(s,t,p))))));
@for(teachers(l)for(students(s)for(times(t)for(places(p):x(l,t,p)*y(s,t,p)<=b(l,t)))));
@for(teachers(l)for(students(s)for(times(t)for(places(p):x(l,t,p)*y(s,t,p)<=c(l,d(s))))));
@for(times(t)for(places(p)sum(teachers(l):x(l,t,p))=@floor(3/2)));
@for(teachers(l)for(students(s)for(times(t)for(places(p):x(l,t,p)+y(s,t,p)+a(s,l)<3))));
@for(times(t)for(places(p)sum(students(s):y(s,t,p))<=@floor(5/(2*2)+1)));
@for(times(t)for(places(p)sum(students(s):y(s,t,p))>=@floor(5/(2*2)-1)));
@for(students(s)sum(places(p)sum(times(t):y(s,t,p)))=1);
@for(teachers(l)for(times(t)sum(places(p):x(l,t,p))<=1));
@for(link5(l,t,p)bin(x(l,t,p)));
@for(link6(s,t,p)bin(y(s,t,p)));
data:
a=1 0 0
  0 0 0
  0 0 0
  0 0 0
  0 0 1;
b=0 1
  1 1
  1 0;
c=0 2 1
  1 2 3
  2 0 3;
d=2 1 1 1 3;
enddata
end
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是什么原因？