arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0906.5322math.PRmath.SP
收藏

不可逆马尔可夫链的几何遍历性和谱间隙

Geometric Ergodicity and the Spectral Gap of Non-Reversible Markov Chains

Ioannis Kontoyiannis, Sean P. Meyn

摘要:

我们认为,谱理论的不可逆马尔可夫链往往可以更有效地铸造的框架内的自然相关的加权$L_\infty$空间$L_\infty^V$,而不是通常的希尔伯特空间$L_2=L_2(π)$,其中$π$是不变的测量链。这一观点部分是基于以下结果。一个离散时间马尔可夫链的值在一般的状态空间是几何遍历的当且仅当它的转移核在$L_\infty^V$中允许一个谱间隙。如果链是可逆的,那么用$L_2$代替$L_\infty^V$也是同样的等价,但是在不可逆的情况下,它失败了:存在(必然是不可逆的,几何遍历的)链,其在$L_\infty^V$中允许谱隙,而在$L_2$中不允许。此外,如果链允许在$L_2$中的谱间隙,则对于任何$h\in L_2$存在李雅普诺夫函数$V_h\in L_1$,使得$V_h$支配$h$,并且链允许在$L_\infty^{V_h}$中的谱间隙。还简要讨论了$L_\infty^V$或$L_2$中的光谱间隙的大小与链收敛到平衡态的速率之间的关系。

英文摘要:

We argue that the spectral theory of non-reversible Markov chains may often be more effectively cast within the framework of the naturally associated weighted-$L_\infty$ space $L_\infty^V$, instead of the usual Hilbert space $L_2=L_2(π)$, where $π$ is the invariant measure of the chain. This observation is, in part, based on the following results. A discrete-time Markov chain with values in a general state space is geometrically ergodic if and only if its transition kernel admits a spectral gap in $L_\infty^V$. If the chain is reversible, the same equivalence holds with $L_2$ in place of $L_\infty^V$, but in the absence of reversibility it fails: There are (necessarily non-reversible, geometrically ergodic) chains that admit a spectral gap in $L_\infty^V$ but not in $L_2$. Moreover, if a chain admits a spectral gap in $L_2$, then for any $h\in L_2$ there exists a Lyapunov function $V_h\in L_1$ such that $V_h$ dominates $h$ and the chain admits a spectral gap in $L_\infty^{V_h}$. The relationship between the size of the spectral gap in $L_\infty^V$ or $L_2$, and the rate at which the chain converges to equilibrium is also briefly discussed.

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。

↑