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D.15.2.20 arrIsEssential

Procedure from library arr.lib (see arr_lib).

Usage:
arrIsEssential(A); arrangement A;

Return:
boolean: 1 if arr is essential, i.e. rank of maximal element of poset is dimension

Note:
A has to be non-empty.

Example:
 
LIB "arr.lib";
ring S = 0,(x,y,z),lp;
arr A = ideal(x,y,z);
arr B = ideal(x+y+z,x,y+z);
arrIsEssential(A);
==> 1
arrIsEssential(B);
==> 0
See also: arrCone; arrDecone; arrEssentialize; arrIsEssential; arrRestrict.