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Philippe Sosoe

Publications and source records attributed to Philippe Sosoe.

44 records · Page 3Linked to original sources
arXiv2015

On the Spectrum of Random Anti-symmetric and Tournament Matrices

We consider a discrete, non-Hermitian random matrix model, which can be expressed as a shift of a rank-one perturbation of an anti-symmetric matrix. We show that, asymptotically almost surely, the real parts of the eigenvalues of the non-Hermitian matrix around any fixed index remain interlaced with those of the anti-symmetric matrix. Along the way, we show that some tools recently developed to study the eigenvalue distributions of Hermitian matrices extend to the anti-symmetric setting.

math.PR↗
arXiv2015

On the chemical distance in critical percolation

We consider two-dimensional critical bond percolation. Conditioned on the existence of an open circuit in an annulus, we show that the ratio of the expected size of the shortest open circuit to the expected size of the innermost circuit tends to zero as the side length of the annulus tends to infinity, the aspect ratio remaining fixed. The same proof yields a similar result for the lowest open crossing of a rectangle. In this last case, we answer a question of Kesten and Zhang by showing in addition that the ratio of the length of the shortest crossing to the length of the lowest tends to zero in probability. This suggests that the chemical distance in critical percolation is given by an exponent strictly smaller than that of the lowest path.

math.PR↗
arXiv2014

Subdiffusive concentration in first-passage percolation

We prove exponential concentration in i.i.d. first-passage percolation in $Z^d$ for all $d \geq 2$ and general edge-weights $(t_e)$. Precisely, under an exponential moment assumption $E e^{αt_e}< \infty$ for some $α>0$) on the edge-weight distribution, we prove the inequality $$ P(|T(0,x)-E T(0,x)| \geq λ\sqrt{\frac{|x|}{log |x|}}) \leq ce^{-c' λ}, |x|>1 $$ for the point-to-point passage time $T(0,x)$. Under a weaker assumption $E t_e^2(\log t_e)_+< \infty$ we show a corresponding inequality for the lower-tail of the distribution of $T(0,x)$. These results extend work of Benaim-Rossignol to general distributions.

math.PR↗
arXiv2014

Sublinear variance in first-passage percolation for general distributions

We prove that the variance of the passage time from the origin to a point x in first-passage percolation on Z^d is sublinear in the distance to x when d \geq 2, obeying the bound Cx/(log x), under minimal assumptions on the edge-weight distribution. The proof applies equally to absolutely continuous, discrete and singular continuous distributions and mixtures thereof, and requires only 2+log moments. The main result extends work of Benjamini-Kalai-Schramm and Benaim-Rossignol.

math.PR↗
arXiv2013

Convergence of the eigenvalue density for beta-Laguerre ensembles on short scales

In this note, we prove that the normalized trace of the resolvent of the beta-Laguerre ensemble eigenvalues is close to the Stieltjes transform of the Marchenko-Pastur (MP) distribution with very high probability, for values of the imaginary part greater than m^{-1+ε}. As an immediate corollary, we obtain convergence of the one-point density to the MP law on short scales. The proof serves to illustrate some simplifications of the method introduced in our previous work to prove a local semi-circle law for Gaussian beta-ensembles.

math.PR↗
arXiv2012

Local semicircle law in the bulk for Gaussian $β$-ensemble

We use the tridiagonal matrix representation to derive a local semicircle law for Gaussian beta ensembles at the optimal level of $n^{-1+δ}$ for any $δ> 0$. Using a resolvent expansion, we first derive a semicircle law at the intermediate level of $n^{-1/2+δ}$; then an induction argument allows us to reach the optimal level. This result was obtained in a different setting, using different methods, by Bourgade, Erdös, and Yau and in Bao and Su. Our approach is new and could be extended to other tridiagonal models.

math.PR↗
arXiv2012

Subdiffusivity of random walk on the 2D invasion percolation cluster

We derive "quenched" subdiffusive lower bounds for the exit time tau(n) from a box of size n for the simple random walk on the planar invasion percolation cluster. The first part of the paper is devoted to proving an almost sure analog of H. Kesten's subdiffusivity theorem for the random walk on the incipient infinite cluster and the invasion percolation cluster using ideas of M. Aizenman, A. Burchard and A. Pisztora. The proof combines lower bounds on the instrinsic distance in these graphs and general inequalities for reversible Markov chains. In the second part of the paper, we present a sharpening of Kesten's original argument, leading to an explicit almost sure lower bound for tau(n) in terms of percolation arm exponents. The methods give tau(n) \geq n^{2+epsilon_0 + kappa}, where epsilon_0>0 depends on the instrinsic distance and (assuming the exact value of the backbone exponent) kappa can be taken to be 17/384 on the hexagonal lattice.

math.PR↗