Abstract
The convexity theory for oriented matroids, first developed by Las Vergnas [17], provides the framework for a new computational approach to the Steinitz problem [13]. We describe an algorithm which, for a given combinatorial (d − 2)-sphereS withn vertices, determines the setC d,n(S) of rankd oriented matroids withn points and face latticeS. SinceS is polytopal if and only if there is a realizableM εC d,n(S), this method together with the coordinatizability test for oriented matroids in [10] yields a decision procedure for the polytopality of a large class of spheres. As main new result we prove that there exist 431 combinatorial types of neighborly 5-polytopes with 10 vertices by establishing coordinates for 98 “doubted polytopes” in the classification of Altshuler [1]. We show that for alln ≧k + 5 ≧8 there exist simplicialk-spheres withn vertices which are non-polytopal due to the simple fact that they fail to be matroid spheres. On the other hand, we show that the 3-sphereM 9963 with 9 vertices in [2] is the smallest non-polytopal matroid sphere, and non-polytopal matroidk-spheres withn vertices exist for alln ≧k + 6 ≧ 9.
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References
A. Altshuler,Neighborly 4-polytopes and neighborly combinatorial 3-manifolds with ten vertices, Can. J. Math.29 (1977), 400–420.
A. Altshuler, J. Bokowski and L. Steinberg,The classification of simplicial 3-spheres with nine vertices into polytopes and nonpolytopes, Discrete Math.31 (1980), 115–124.
C. Antonin,Ein Algorithmusansatz für Realisierungsfragen im E d, getestet an kombinatorischen 3-Sphären, Staatsexamensarbeit, Bochum, 1982.
L. J. Billera and B. S. Munson,Triangulations of oriented matroids and convex polytopes, SIAM J. Algebraic Discrete Methods5 (1984), 515–525.
R. G. Bland and M. Las Vergnas,Orientability of matroids, J. Comb. Theory B24 (1978), 94–123.
J. Bokowski, G. Ewald and P. Kleinschmidt,On combinatorial affine automorphisms of polytopes, Isr. J. Math.47 (1984), 123–130.
J. Bokowski and K. Garms,Altshuler’s sphere M(425/10) is not polytopal, European J. Math., to appear.
J. Bokowski and I. Shemer,Neighborly 6-polytopes with 10vertices, Isr. J. Math., to appear.
J. Bokowski and B. Sturmfels,Oriented matroids and chirotopes — problems of geometric realizability, manuscript, Darmstadt, 1985.
J. Bokowski and B. Sturmfels,Coordinatization of oriented matroids, manuscript, Darmstadt, 1985.
R. Cordovil,Oriented matroids of rank 3 and arrangements of pseudolines, Ann. Discrete Math.17 (1983), 219–223.
R. Cordovil and P. Duchet,On the number of sign-invariant pairs of points in oriented matroids, manuscript, Lisboa/Paris, 1985.
G. Ewald, P. Kleinschmidt, U. Pachner and C. Schulz,Neuere Entwicklungen in der kombinatorischen Konvexgeometrie, inContributions to Geometry, Proceedings of the Geometry Symposium, Birkhäuser, Basel, Siegen, 1978.
J. E. Goodman and R. Pollack,Proof of Grünbaum’s conjecture on the stretchability of certain arrangements of pseudolines, J. Comb. Theory A29 (1980), 385–390.
B. Grünbaum,Convex Polytopes, Wiley-Intersciences, London-New York-Sydney, 1967.
P. Kleinschmidt,Sphären mit wenigen Ecken, Geom. Dedicata5 (1976), 307–320.
M. Las Vergnas,Convexity in oriented matroids, J. Comb. Theory B29 (1980), 231–243.
A. Mandel,Topology of oriented matroids, Ph.D. thesis, University Waterloo, 1982.
P. Mani,Spheres with few vertices, J. Comb. Theory A13 (1972), 346–352.
B. S. Munson,Face lattices of oriented matroids, Ph.D. thesis, Cornell University, Ithaca, N.Y., 1981.
I. Shemer,Neighborly polytopes, Isr. J. Math.43 (1982), 291–314.
B. Sturmfels,Zur linearen Realisierbarkeit orientierter Matroide, Diplomarbeit, Darmstadt, 1985.
A. Tarski,A decision method for elementary algebra and geometry, University of California Press, Berkeley and Los Angeles, 1951.
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Bokowski, J., Sturmfels, B. Polytopal and nonpolytopal spheres an algorithmic approach. Israel J. Math. 57, 257–271 (1987). https://doi.org/10.1007/BF02766213
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DOI: https://doi.org/10.1007/BF02766213