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arXiv 2402.01299math.PR
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三角Pólya urn的几乎必然收敛与矩收敛

Almost sure and moment convergence for triangular Pólya urns

Svante Janson

AI总结:

本文研究三角Pólya urn,在极弱条件下证明了球数的几乎必然强极限定理及平衡urn的矩收敛,并利用鞅方法将结果推广至带减法的urn。

摘要:

我们考虑三角Pólya urn,并在极弱条件下证明形如$X_{ni}/a_{ni}\to \mathcal{X}_i$ a.s.的一般强极限定理,其中$X_{ni}$是抽取$n$次后颜色$i$的球数;常数$a_{ni}$是显式的且具有$n^α\log^γn$的形式;极限a.s.为正,可能为确定值或随机值,但通常是未知的。在弱条件下该结果可推广至带减法的urn,但反例表明仍需某些条件。对于平衡urn,若替换矩阵具有相应的矩,我们也在主要结果中证明了矩收敛。证明基于使用鞅方法研究对应的连续时间urn,并在其中证明相应结果。为方便起见,我们假设所有替换均具有有限二阶矩。

英文摘要:

We consider triangular Pólya urns and show under very weak conditions a general strong limit theorem of the form $X_{ni}/a_{ni}\to \mathcal{X}_i$ a.s., where $X_{ni}$ is the number of balls of colour $i$ after $n$ draws; the constants $a_{ni}$ are explicit and of the form $n^α\log^γn$; the limit is a.s. positive, and may be either deterministic or random, but is in general unknown. The result extends to urns with subtractions under weak conditions, but a counterexample shows that some conditions are needed. For balanced urns we also prove moment convergence in the main results if the replacements have the corresponding moments. The proofs are based on studying the corresponding continuous-time urn using martingale methods, and showing corresponding results there. We assume for convenience that all replacements have finite second moments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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