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D.13.3.4 minimalAfaces

Procedure from library gitfan.lib (see gitfan_lib).

Usage:
minimalAfaces(listOfAfaces); listOfAfaces: list

Purpose:
Returns a list of all minimal a-faces. Note that listOfAfaces must only contain afaces which project to full dimension.

Return:
a list of intvecs

Example:
 
LIB "gitfan.lib";
setcores(4);
==> 4
ring R = 0,T(1..10),wp(1,1,1,1,1,1,1,1,1,1);
ideal J =
T(5)*T(10)-T(6)*T(9)+T(7)*T(8),
T(1)*T(9)-T(2)*T(7)+T(4)*T(5),
T(1)*T(8)-T(2)*T(6)+T(3)*T(5),
T(1)*T(10)-T(3)*T(7)+T(4)*T(6),
T(2)*T(10)-T(3)*T(9)+T(4)*T(8);
intmat Q[5][10] =
1, 1, 1, 1, 0, 0, 0, 0, 0, 0,
1, 0, 0, 0, 1, 1, 1, 0, 0, 0,
0, 1, 1, 0, 0, 0, -1, 1, 0, 0,
0, 1, 0, 1, 0, -1, 0, 0, 1, 0,
0, 0, 1, 1, -1, 0, 0, 0, 0, 1;
list AF= afaces(J,nrows(Q));
size(AF);
==> 81
AF=fullDimImages(AF,Q);
size(AF);
==> 36
AF=minimalAfaces(AF);
size(AF);
==> 25

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