# Motivic Poincar\'e series of cusp surface singularities

## TL;DR

This paper introduces motivic Poincaré series for cusp surface singularities, extending the theory beyond rational homology sphere links, and provides explicit combinatorial formulas for these series.

## Contribution

It defines and proves the equality of motivic analytical and topological Poincaré series for cusp singularities, with explicit combinatorial expressions.

## Key findings

- Motivic Poincaré series are well-defined for cusp singularities.
- Analytical and topological motivic series are proven to be equal.
- Explicit combinatorial formulas are provided for these series.

## Abstract

We target multivariable series associated with resolutions of complex analytic normal surface singularities. In general, the equivariant multivariable analytical and topological Poincar\'e series are well-defined and have good properties only if the link is a rational homology sphere. We wish to create a model when this assumption is not valid: we analyse the case of cusps. For such germs we define even the motivic versions of these two series, we prove that they are equal, and we provide explicit combinatorial expression for them. This is done via a motivic multivariable series associated with the space of effective Cartier divisors of the reduced exceptional curve.