CONE OF FLAG l-VECTORS OF HALF-EULERIAN POSETS OF RANK 6 Extreme rays, given by interval systems: ( 1): 0 ( 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] Flag l-vectors The entries l(S) in the flag l-vector are represented by variables xi as follows: x1 = l(emptyset) x2 = l(12) x3 = l(23) x4 = l(34) x5 = l(1234) x6 = l(45) x7 = l(1245) x8 = l(2345) Flag l-vectors of extremes: ( 1) 1 0 0 0 0 0 0 0 ( 2) 1 -1 0 0 0 0 0 0 ( 3) 1 0 -1 0 0 0 0 0 ( 4) 1 0 0 -1 0 0 0 0 ( 5) 1 -1 0 -1 1 0 0 0 ( 6) 1 0 0 0 -1 0 0 0 ( 7) 1 0 0 0 0 -1 0 0 ( 8) 1 -1 0 0 0 -1 1 0 ( 9) 1 0 -1 0 0 -1 0 1 (10) 1 0 0 0 0 0 0 -1 Inequalities for the cone: (L 1) +x4 <= 0 (L 2) +x3 <= 0 (L 3) +x6+x7 <= 0 (L 4) +x4+x5 <= 0 (L 5) +x3 +x8 <= 0 (L 6) +x2 +x7 <= 0 (L 7) +x6+x7+x8 <= 0 (L 8) +x2 +x5 +x7 <= 0 (L 9) -x7 <= 0 (L 10) -x1-x2-x3-x4-x5-x6-x7-x8 <= 0 Strong validity table. A * in row i and column j indicates that extreme (j) lies on the facet given by inequality (L 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 | ***.. ***** : 8 2 | **.** ***.* : 8 3 | ***** *.*.* : 8 4 | ***.* .**** : 8 5 | **.** ****. : 8 6 | *.**. ***** : 8 7 | ***** *.**. : 8 8 | *.*** .**** : 8 9 | ***** **.** : 9 10 | .**** ***** : 9 ................. # | 98888 88988