# Kantorovich problems and conditional measures depending on a parameter

## TL;DR

This paper investigates the measurable dependence of measures on parameters in optimal transportation and conditional measures, providing broad conditions for Borel measurability and applications to parametrization of measures.

## Contribution

It establishes new sufficient conditions for the Borel measurability of conditional measures and optimal transports depending on parameters, advancing the understanding of measure parametrization.

## Key findings

- Provided broad conditions for the existence of measurable conditional measures.
- Established sufficient conditions for Borel measurability of optimal transports and costs.
- Demonstrated measurable parametrization of measures via Skorohod's approach.

## Abstract

We study measurable dependence of measures on a parameter in the following two classical problems: constructing conditional measures and the Kantorovich optimal transportation. We obtain broad sufficient conditions for the existence of conditional probabilities measurably depending on a parameter in the case of parametric families of measures and mappings. A~particular emphasis is made on the Borel measurability (which cannot be always achieved). Our second main result gives sufficient conditions for the Borel measurability of optimal transports and transportation costs with respect to a parameter in the case where marginal measures and cost functions depend on a parameter. As a corollary we obtain the Borel measurability with respect to the parameter for conditional measures of optimal plans. Finally, we show that the Skorohod parametrization of measures by mappings can be also made measurable with respect to a parameter.