Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Riesz transforms of a general Ornstein--Uhlenbeck semigroup   We consider Riesz transforms of any order associated to an
Ornstein--Uhlenbeck operator $\mathcal L$, with covariance $Q$ given by a real,
symmetric and positive definite matrix, and with drift $B$ given by a real
matrix whose eigenvalues have negative real parts. In this general Gaussian
context, we prove that a Riesz transform is of weak type $(1,1)$ with respect
to the invariant measure if and only if its order is at most $2$.

27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int