  This publication presents a relation computation or calculus for
international relations using a mathematical modeling. It examined trust for
international relations and its calculus, which related to Bayesian inference,
Dempster-Shafer theory and subjective logic. Based on an observation in the
literature, we found no literature discussing the calculus method for the
international relations. To bridge this research gap, we propose a relation
algebra method for international relations computation. The proposed method
will allow a relation computation which is previously subjective and
incomputable. We also present three international relations as case studies to
demonstrate the proposed method is a real-world scenario. The method will
deliver the relation computation for the international relations that to
support decision makers in a government such as foreign ministry, defense
ministry, presidential or prime minister office. The Department of Defense
(DoD) may use our method to determine a nation that can be identified as a
friendly, neutral or hostile nation.
