Training a 3-node neural network is NP-complete

Blum, A., & Rivest, R. L. (1988). Training a 3-node neural network is NP-complete. In Proceedings of the 1st Annual Workshop on Computational Learning Theory, COLT 1988 (pp. 9–18). Association for Computing Machinery, Inc. https://doi.org/10.1007/3-540-56483-7_20