# Bjorner's example of shellable but not extendably shellable
# 2-complex. Taken from
# "The homology and shellability of matroids and geometric lattices,"
# in "Matroid Applications", N.White ed., Cambridge Univ. Press (1992),
# 226-283. (Exercise 7.37.)
# This is a projective plane plus additional facet "1 2 3".
# f=(1,6,15,11).
1 2 3
1 2 5
1 2 6
1 3 4
1 3 6
1 4 5
2 3 4
2 3 5
2 4 6
3 5 6
4 5 6