arXiv subjects
Publications and source records attributed to Mohammad Ansari.
Let $\Bbb D$ be the open unit disk in the complex plane. In this note, for the Carleson set $S(b,h)$ and the Carleson window $W(b,h)$ which are particular subsets of $\Bbb D$, we find conditions on $h$ under which we have $W(b,h/c)\subset S(b,h)\subset W(b,ch)$ for some $c>1$.
We give some basic properties of strongly topologically transitive, supermixing, and hypermixing maps on general topological spaces. Then we present some other results for which our mappings need to be continuous.
In this article, first we show that the Fréchet space $H(\Bbb D)$ cannot support strongly supercyclic weighted composition operators. Then we compute the constant $ε$ for weighted backward shifts on $\ell^p$ ($1\le p<\infty$) and $c_0$. This constant is used to find strongly hypercyclic scalar multiples of non-invertible strongly supercyclic Banach space operators. Finally, we give an affirmative answer to a recent open question concerning supercyclic vectors.
We apply the well-known and also the newly introduced notions from bounded linear dynamics to unbounded linear operators. We present a hypermixing criterion similar to that given for bounded linear operators and then we show that the derivative operator in $H^2$, the Laplacian operator in $L^2(Ω)$, and all unbounded weighted translations in $L_p(0,\infty)$ and $C_0[0,\infty)$ are hypermixing.
We give an affirmative answer to a question asked by Faghih-Ahmadi and Hedayatian regarding supercyclic vectors. We show that if $\mathcal X$ is an infinite-dimensional normed linear space and $T$ is a supercyclic operator on $\mathcal X$, then for any supercyclic vector $x$ for $T$, there exists a strictly increasing sequence $(n_k)_k$ of positive integers such that the closed linear span of the set $\{T^{n_k}x: k\ge 1\}$ is not the whole $\mathcal X$.
We present here a compact and self-contained review of recently developed Keldysh formalism for multiple parallel worlds. The formalism has been applied to consistent quantum evaluation of the flows of informational quantities, in particular, to evaluation of Renyi and Shannon entropy flows. We start with the formulation of standard and extended Keldysh technique in single world in a form convenient for our presentation. We explain the use of Keldysh contours encompassing multiple parallel worlds In the end, we shortly summarize the concrete results obtained with the method.