Nous donnons une estimation polynomiale pour la fonction de densité spectrale d’une matrice sur l’algèbre complexe du groupe . Ce résultat donne une borne inférieure explicite à l’invariant de Novikov-Shubin associé à la matrice, montrant en particulier que l’invariant de Novikov-Shubin est strictement positif.
We give a polynomial bound on the spectral density function of a matrix over the complex group ring of . It yields an explicit lower bound on the Novikov-Shubin invariant associated to this matrix showing in particular that the Novikov-Shubin invariant is larger than zero.
@article{AMBP_2015__22_1_73_0, author = {L\"uck, Wolfgang}, title = {Estimates for spectral density functions of matrices over $\mathbb{C}[\mathbb{Z}^d]$}, journal = {Annales math\'ematiques Blaise Pascal}, volume = {22}, year = {2015}, pages = {73-88}, doi = {10.5802/ambp.346}, language = {en}, url = {http://dml.mathdoc.fr/item/AMBP_2015__22_1_73_0} }
Lück, Wolfgang. Estimates for spectral density functions of matrices over $\mathbb{C}[\mathbb{Z}^d]$. Annales mathématiques Blaise Pascal, Tome 22 (2015) pp. 73-88. doi : 10.5802/ambp.346. http://gdmltest.u-ga.fr/item/AMBP_2015__22_1_73_0/
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