# Operational locality in global theories

## TL;DR

This paper explores how operational notions of locality can be derived from signaling conditions between agents, providing a new perspective on the relationship between local actions and observations in physical theories.

## Contribution

It introduces an operational model for agents' state spaces and actions, linking locality to signaling and proposing a primitive based on transformation commutation.

## Key findings

- Operational model for agent state spaces and actions
- Secrecy conditions relate to signaling and locality
- Discussion on commutation of transformations as a primitive

## Abstract

Within a global physical theory, a notion of locality allows us to find and justify information-processing primitives, like non-signalling between distant agents. Here we propose exploring the opposite direction: to take agents as the basic building blocks through which we test a physical theory, and recover operational notions of locality from signalling conditions. First we introduce an operational model for the effective state spaces of individual agents, as well as the range of their actions. We then formulate natural secrecy conditions between agents and identify the aspects of locality relevant for signalling. We discuss the possibility of taking commutation of transformations as a primitive of physical theories, as well as applications to quantum theory and generalized probability frameworks. This "it from bit" approach establishes an operational connection between local action and local observations, and gives a global interpretation to concepts like discarding a subsystem or composing local functions.