arXiv subjects

Jeffrey McGowan

Publications and source records attributed to Jeffrey McGowan.

5 recordsLinked to original sources

arXiv2020

Lens spaces isospectral on forms but not on functions

This paper means to correct an error by the authors for the composite $q$ case in the paper "Lens Spaces, Isospectral on Forms but not on Functions", published in LMS J. Comput. Math.} 9 (2006), 270-286. All calculations and examples presented in \cite{GM} for prime $q$ remain valid, and we include detailed calculations below justifying this. Our original mistake was to conclude that Formula (3.11) \cite[p. 399]{Ikeda} remained true for all $q$ when in fact it is only valid if $q$ is prime. This means formulas (3) and (4) in \cite{GM} must be reworked to account for complications when $q$ is composite.

math.DG↗

arXiv2010

Regular trees in random regular graphs

We investigate the size of the embedded regular tree rooted at a vertex in a $d$ regular random graph. We show that almost always, the radius of this tree will be ${1/2}\log n$, where $n$ is the number of vertices in the graph. And we give an asymptotic estimate for Gauss' Hypergeometric Function.

math.CO↗

arXiv2005

An elementary proof that random Fibonacci sequences grow exponentially

We consider random Fibonacci sequences given by $x_{n+1}=\pm βx_{n}+x_{n-1}$. Viswanath (\cite{viswanath}), following Furstenberg (\cite{furst}) showed that when $β= 1$, $\lim_{n\to \infty}|x_{n}|^{1/n}=1.13...$, but his proof involves the use of floating point computer calculations. We give a completely elementary proof that $1.25577 \ge (E(|x_{n}|))^{1/n} \ge 1.12095$ where $E(|x_{n}|)$ is the expected value for the absolute value of the $n$th term in a random Fibonacci sequence. We compute this expected value using recurrence relations which bound the sum of all possible $n$th terms for such sequences. In addition, we give upper an lower

math.NT↗

arXiv2005

The length of closed geodesics on random Riemann Surfaces

Short geodesics are important in the study of the geometry and the spectra of Riemann surfaces. Bers' theorem gives a global bound on the length of the first $3g-3$ geodesics. We use the construction of Brooks and Makover of random Riemann surfaces to investigate the distribution of short ($< \log (g)$) geodesics on a random Riemann surfaces. We calculate the expected value of the shortest geodesic, and show that if one orders prime non-intersecting geodesics by length $γ_1\le γ_2\le ... \le γ_i ,...$, then for fixed $k$, if one allows the genus to go to infinity, the length of $γ_{k}$ is independent of the genus.

math.DG↗

arXiv2004

Bounds on Accumulation Rates of Eigenvalues on Manifolds with Degenerating Metrics

We consider a family of manifolds with a class of degenerating warped product metrics $g_ε=ρ(ε,t)^{2a}dt^2 +ρ(ε,t)^{2b}ds_M^2$, with $M$ compact, $ρ$ homogeneous degree one, $a \le -1$ and $b > 0$. We study the Laplace operator acting on $L^{2}$ differential $p$-forms and give sharp accumulation rates for eigenvalues near the bottom of the essential spectrum of the limit manifold with metric $g_{0}$.

math.DG↗