@article{McCune1997OtterT,
title={Otter - The CADE-13 Competition Incarnations},
author={William McCune and Larry Wos},
journal={Journal of Automated Reasoning},
year={1997},
volume={18},
pages={211-220}
}

This article discusses the two incarnations of Otter entered in the CADE-13 Automated Theorem Proving System Competition. Also presented are some historical background, a summary of applications that have led to new results in mathematics and logic, and a general discussion of Otter.Â