# Parametric pseudodifferential operators with point-singularity in the covariable

## TL;DR

This paper develops a new calculus for parameter-dependent pseudodifferential operators with point singularities, enabling analysis of resolvent-trace expansions and invertibility of Toeplitz-type operators.

## Contribution

It introduces a novel class of symbols with point singularities and a corresponding calculus, extending Grubb's framework and connecting to the Grubb-Seeley expansion.

## Key findings

- Recovered the resolvent-trace expansion for elliptic operators.
- Established invertibility criteria for Toeplitz-type operators.
- Extended pseudodifferential calculus to include point-singular symbols.

## Abstract

Starting out from a new description of a class of parameter-dependent pseudodifferential operators with finite regularity number due to G. Grubb, we introduce a calculus of parameter-dependent, poly-homogeneous symbols whose homogeneous components have a particular type of point-singularity in the covariable-parameter space. Such symbols admit intrinsically a second kind of expansion which is closely related to the expansion in the Grubb-Seeley calculus and permits to recover the resolvent-trace expansion for elliptic pseudodifferential oerators originally proved by Grubb-Seeley. Another application is the invertibility of parameter-dependent operators of Toeplitz type, i.e., operators acting in subspaces determined by zero-order pseudodifferential idempotents.