Suppose $F:=(f_1,\ldots,f_n)$ is a system of random $n$variate polynomials with $f_i$ having degree $\leq\!d_i$ and the coefficient of $x^{a_1}_1\cdots x^{a_n}_n$ in $f_i$ being an independent complex Gaussian of mean $0$ and variance $\frac{d_i!}{a_1!\cdots a_n!\left(d_i\sum^n_{j=1}a_j \right)!}$. Recent progress on Smale's 17$\thth$ Problem by Lairez  building upon seminal work of Shub, Beltran, Pardo, B\"{u}rgisser, and Cucker  has resulted in a deterministic algorithm that finds a single (complex) approximate root of $F$ using just $N^{O(1)}$ arithmetic operations on average, where $N\!:=\!\sum^n_{i=1}\frac{(n+d_i)!}{n!d_i!}$ ($=n(n+\max_i d_i)^{O(\min\{n,\max_i d_i)\}}$) is the maximum possible total number of monomial terms for such an $F$. However, can one go faster when the number of terms is smaller, and we restrict to real coefficient and real roots? And can one still maintain averagecase polynomialtime with more general probability measures? We show the answer is yes when $F$ is instead a binomial system  a case whose numerical solution is a key step in polyhedral homotopy algorithms for solving arbitrary polynomial systems. We give a deterministic algorithm that finds a real approximate root (or correctly decides there are none) using just $O(n^3\log^2(n\max_i d_i))$ arithmetic operations on average. Furthermore, our approach allows Gaussians with arbitrary variance. We also discuss briefly the obstructionsmore »
Topologies of Random Geometric Complexes on Riemannian Manifolds in the Thermodynamic Limit
Abstract We investigate the topologies of random geometric complexes built over random points sampled on Riemannian manifolds in the socalled “thermodynamic” regime. We prove the existence of universal limit laws for the topologies; namely, the random normalized counting measure of connected components (counted according to homotopy type) is shown to converge in probability to a deterministic probability measure. Moreover, we show that the support of the deterministic limiting measure equals the set of all homotopy types for Euclidean connected geometric complexes of the same dimension as the manifold.
 Award ID(s):
 1653552
 Publication Date:
 NSFPAR ID:
 10286247
 Journal Name:
 International Mathematics Research Notices
 ISSN:
 10737928
 Sponsoring Org:
 National Science Foundation
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