# Projective limits of local shift morphism

## TL;DR

This paper introduces the concept of projective limits of local shift morphisms, providing a differential structure and applying it to Poisson tensors, exemplified by the KdV equation on the circle.

## Contribution

It defines projective limits of local shift morphisms and applies this framework to shift Poisson tensors, including a case study on the KdV equation.

## Key findings

- Defined projective limits of local shift morphisms with differential structure
- Characterized shift Poisson tensors as antisymmetric morphisms with vanishing Schouten bracket
- Applied the framework to compatible Poisson tensors for the KdV equation on the circle

## Abstract

We define the notion of projective limit of local shift morphisms of type $\left( r,s\right) $ and endow the space of such mathematical objects with an adapted differential structure. The notion of shift Poisson tensor $P$ on a Hilbert tower corresponds to such morphisms which are antisymmetric and whose Schouten bracket $\left[ P,P\right] $ vanishes. We illustrate this notion with the example of the famous KdV equation on the circle $\mathbb{S}^{1}$ for which one can associate a couple of compatible Poisson tensors of this type on the Hilbert tower $\left( H^{n}(\mathbb{S}^{1})\right) _{n\in\mathbb{N}% ^{\ast}}$.