First extension groups of Verma modules and R-polynomials
Journal of Lie theory, Tome 25 (2015) no. 2, pp. 377-393
We study the first extension groups between Verma modules. There was a conjecture which claims that the dimensions of the higher extension groups between Verma modules are the coefficients of R-polynomials defined by Kazhdan-Lusztig. This conjecture was known as the Gabber-Joseph conjecture (although Gabber and Joseph did not state it.) However, Boe gives a counterexample to this conjecture. In this paper, we study how far the dimensions of extension groups from the coefficients of R-polynomials are.
Classification :
17B10, 17B55
Mots-clés : Verma module, Extension groups
Mots-clés : Verma module, Extension groups
@article{JLT_2015_25_2_JLT_2015_25_2_a3,
author = {N. Abe},
title = {First extension groups of {Verma} modules and {\protect\emph{R}-polynomials}},
journal = {Journal of Lie theory},
pages = {377--393},
year = {2015},
volume = {25},
number = {2},
url = {http://geodesic.mathdoc.fr/item/JLT_2015_25_2_JLT_2015_25_2_a3/}
}
N. Abe. First extension groups of Verma modules and R-polynomials. Journal of Lie theory, Tome 25 (2015) no. 2, pp. 377-393. http://geodesic.mathdoc.fr/item/JLT_2015_25_2_JLT_2015_25_2_a3/