The M-property of Flag Varieties
نویسنده
چکیده
We consider arbi ofhigbCnensi088at reaHlagvarietiespPp " an arrangements with the sum of the violation of this the Mayer-Vietoris spectral sequence in aBe term for some class of ikywds: Flag variety, ubcrt cell decom M-property, Mayer-Vietoris spectral sequence. The well-known Smith inequalitv implis that for arr d&$t:ti XR we have C 6i(XR) G C bi(Xcj, where bi denotes the coefficients in Z/22 and XC denotes the complexification of XR (see for example 121). In the particular case of a planar real algebraic cume this inequality is called Hamack's inequality and the planar curves for which Hamack's inequality is in fact the equality are called M-curves. M-curves were studied by several authors (see Cl09 89% m 1.1. l%e main definition A real algebraic variety XR (the set of real points of Xc) is called an M-manifold if c bi(XR) =c bi(X "). (We shall also say that in this case XR has There are several articles by authors from the Leningrad and Go M-surfaces (see [4,12]).
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