Re: [Help-glpk] abs/min/max

[Andrew Makhorin]

> Could you tell me how can I calculate 
> 
> minimize obj :
> max({i in 1..4}: abs(x[i])); 

Note that obj >= x[i] and obj >= -x[i] implies obj >= abs(x[i]), and the
latter for all i implies obj >= max abs(x[i]); thus

s.t. aaa{i in 1..4}: obj >= x[i];
s.t. bbb{i in 1..4}: obj >= -x[i];
minimize obj;

> 
> or
> minimize obj :
> max({i in 1..4}: min(x[i]); 

Over which domain is min(x[i]) calculated?