Singular Manual: arrLattice

D.15.1.38 arrLattice

Procedure from library arr.lib (see arr_lib).

Usage:: arrLattice(arr ARR)
Return:: [arrposet] intersection poset of the arrangement
Note:: The algorithm works by a bottom up approach, i.e. it calculates the

Example:

LIB "arr.lib";
ring r;
arrLattice(arrTypeB(3));
==> 
==> 
==> === Computing poset ===
==> 
==> 
==> rank 2: found 13 flats in 0s
==> rank 3: found 1 flats in 0s
==> 
==> 
==> Matrix tests: 86
==> Given Arrangement:
==> _[1]=x-y
==> _[2]=x+y
==> _[3]=x-z
==> _[4]=x+z
==> _[5]=x
==> _[6]=y-z
==> _[7]=y+z
==> _[8]=y
==> _[9]=z
==> 
==> Corresponding poset:
==> ====== rank 1: 9 flats ======
==>  (1),  (2),  (3),  (4),  (5),  (6),  (7),  (8),  (9), 
==> ====== rank 2: 13 flats ======
==>  (1,2,5,8),  (1,3,6),  (1,4,7),  (1,9),  (2,3,7),  (2,4,6),  (2,9),  (3,4\
   ,5,9),  (3,8),  (4,8),  (5,6),  (5,7),  (6,7,8,9), 
==> ====== rank 3: 1 flats ======
==>  (1,2,3,4,5,6,7,8,9), 
==>