Some theorems on graph congruences Robert Knast — 1983 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications
A semigroup characterization of dot-depth one languages Robert Knast — 1983 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications
Graph congruences and pair testing J. A. Brzozowski; Robert Knast — 1986 RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications