348,681 research outputs found
Tensor products of homotopy Gerstenhaber algebras
On the tensor product of two homotopy Gerstenhaber algebras we construct a
Hirsch algebra structure which extends the canonical dg algebra structure. Our
result applies more generally to tensor products of "level 3 Hirsch algebras"
and also to the Mayer-Vietoris double complex.Comment: 13 pages; new Remark 5.4, minor change
Topological Prismatoids and Small Simplicial Spheres of Large Diameter
We introduce topological prismatoids, a combinatorial abstraction of the
(geometric) prismatoids recently introduced by the second author to construct
counter-examples to the Hirsch conjecture. We show that the `strong -step
Theorem' that allows to construct such large-diameter polytopes from
`non--step' prismatoids still works at this combinatorial level. Then, using
metaheuristic methods on the flip graph, we construct four combinatorially
different non--step -dimensional topological prismatoids with
vertices. This implies the existence of -dimensional spheres with
vertices whose combinatorial diameter exceeds the Hirsch bound. These examples
are smaller that the previously known examples by Mani and Walkup in 1980 (
vertices, dimension ).
Our non-Hirsch spheres are shellable but we do not know whether they are
realizable as polytopes.Comment: 20 pages. Changes from v1 and v2: Reduced the part on shellability
and general improvement to accesibilit
What does Hirsch index evolution explain us? A case study: Turkish Journal of Chemistry
The evolution of Turkish Journal of Chemistry (Turk J. Chem) Hirsch index
(h-index) over the period 1995-2005 is studied and determined in the case of
the self and without self-citations. It is seen that the effect of Hirsch index
of Turk J. Chem has a highly positive trend during the last five years. It
proves that Turk J. Chem is improving itself both in quantity and quality since
h-index reflects peer review, and peer review reflects research quality of a
journal.Comment: 5 pages, 3 figure
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