# Time-Stamped Claim Logic

## TL;DR

This paper introduces Time-Stamped Claim Logic, a formal system for reasoning about evidence from multiple sources with trust considerations, demonstrated through a cyber-attribution case study.

## Contribution

It defines a new logic with a sound and complete calculus for managing and resolving contradictory evidence based on trustworthiness.

## Key findings

- The logic reduces evidence set size effectively.
- It ensures consistency with trust relations.
- Applied successfully in a cyber-attribution case study.

## Abstract

The main objective of this paper is to define a logic for reasoning about distributed time-stamped claims. Such a logic is interesting for theoretical reasons, i.e., as a logic per se, but also because it has a number of practical applications, in particular when one needs to reason about a huge amount of pieces of evidence collected from different sources, where some of the pieces of evidence may be contradictory and some sources are considered to be more trustworthy than others. We introduce the Time-Stamped Claim Logic including a sound and complete sequent calculus that allows one to reduce the size of the collected set of evidence and removes inconsistencies, i.e., the logic ensures that the result is consistent with respect to the trust relations considered. In order to show how Time-Stamped Claim Logic can be used in practice, we consider a concrete cyber-attribution case study.