CONE OF SPARSE f-VECTORS OF HALF-EULERIAN POSETS OF RANK 6 Extreme rays, given by interval systems: ( 1): empty family ( 2): [1,2] ( 3): [2,3] ( 4): [3,4] ( 5): [1,2][3,4] ( 6): [1,4] ( 7): [4,5] ( 8): [1,2][4,5] ( 9): [2,3][4,5] (10): [2,5] Sparse flag f-vectors The entries f(S) in the sparse flag vector are represented by variables xi as follows: x1 = f(emptyset) x2 = f(1) x3 = f(2) x4 = f(3) x5 = f(13) x6 = f(4) x7 = f(14) x8 = f(24) Sparse flag f-vectors of extremes: ( 1) 1 1 1 1 1 1 1 1 ( 2) 0 1 1 0 1 0 1 1 ( 3) 0 0 1 1 1 0 0 1 ( 4) 0 0 0 1 1 1 1 1 ( 5) 0 0 0 0 1 0 1 1 ( 6) 0 1 1 1 1 1 1 1 ( 7) 0 0 0 0 0 1 1 1 ( 8) 0 0 0 0 0 0 1 1 ( 9) 0 0 0 0 0 0 0 1 (10) 0 0 1 1 1 1 1 1 Inequalities for the cone: (F 1) -x1 <= 0 (F 2) +x7-x8 <= 0 (F 3) +x4-x5 <= 0 (F 4) +x3 -x5 <= 0 (F 5) +x2-x3 <= 0 (F 6) +x1-x2 <= 0 (F 7) -x4+x5+x6-x7 <= 0 (F 8) +x4 -x6+x7-x8 <= 0 (F 9) +x2-x3+x4 -x6 <= 0 (F 10) +x1-x2+x3-x4 <= 0 Strong validity table. A * in row i and column j indicates that extreme (j) lies on the facet given by inequality (F i). The right-most column gives the number of extremes on each facet. The bottom two rows, read vertically, give the number of facets containing each extreme. \ P | | \ O | | I \ I | | N \ N | 1 6 | # E \ T | | Q \ S | | S \ | | \ | | --------------------------- 1 | .**** ***** : 9 2 | **.** ***.* : 8 3 | *.**. ***** : 8 4 | ***.. ***** : 8 5 | **.** ****. : 8 6 | *.*** .**** : 8 7 | ***** **.** : 9 8 | ***** *.*.* : 8 9 | ***** *.**. : 8 10 | ***.* .**** : 8 ................. # | 98888 88988