Font Size: 

Chess has been always a challenging subject of various computer analyses and methodologies, and they often brought more general advances in the related computer science fields, such as search strategies, AI planning, data-mining, etc. However, interactive theorem proving has hardly been applied to chess. In this paper we present our formalization, within the Coq proof assistant, of one fragment of the chess game - KRK chess ending and several conjectures relevant for this endgame. We show that most of the considered notions and conjectures can be expressed in a simple theory such as linear arithmetic. In addition, in this paper we present a formalization of Bratko's strategy for the KRK endgame. The presented formalization will serve as a key step towards formal correctness proof for Bratko's strategy.