正規形がないときでもコヒーレンス

• Title: Coherence without unique normal forms (Submitted on 30 May 2007)
• Authors: Jonathan A. Cohen
• URL: http://arxiv.org/abs/0705.4334
• Pages: 23

Melliesの"MacLane's coherence theorem expressed as a word problem"（http://hal.archives-ouvertes.fr/docs/00/15/42/13/PDF/25_0310mn_Mellies.pdf）と一緒に読むといいかもしれない。