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EJC
2008
14 years 9 months ago
2008
We provide bounds for the product of the lengths of distinguished shortest paths in a finite network induced by a triangulation of a topological planar quadrilateral.
EJC
2007
14 years 9 months ago
2007
Given a graph we show how to construct a family of manifolds whose Euler characteristics are the values of the chromatic polynomial of the graph at various integers. The manifolds...
EJC
2007
14 years 9 months ago
2007
We sharpen a result of Hansel on separating set systems. We also extend a theorem of Spencer on completely separating systems by proving an analogue of Hansel’s result.
EJC
2007
14 years 9 months ago
2007
We consider in this work the enumeration of involutions by descent sets, and based on that, by descent numbers. Formulas of the number of involutions with a prescribed descent set...
EJC
2007
14 years 9 months ago
2007
It is known that the area of all Catalan paths of length n is equal to 4n − `2n+1 n ´ , which coincides