This volume contains the papers presented at the Third Combinatorics, Computability and Logic (DMTCS'01) conference, These papers cover topics such as abstract data types and specifications algorithms and data structures automata and formal languages computability among others.

The third Discrete Mathematics and Theoretical Computer Science conference (DMTCS'OI) of the Centre for Discrete Mathematics and Theoretical Computer Science of the University of Auckland has been organised at the Faculty of Math- ematics and Computer Science, "Ovidius" University, Constan~a, Romania, with the co-operation of the Maritime Academy "Mircea eel Batran", Constan~a. It was held held in the beautiful Romanian city of Constan~a on the Black Sea. The conference was dedicated to Professor Frank Harary on the occasion of his 80th Birthday. The four invited speakers of the conference were: F. Harary (New Mexico State University, USA), H. Ishihara (Jaist, Japan), P. Odifreddi (Thrin Univer- sity, Italy), 1. Tomescu (Bucharest University, Romania). The Programme Committee consisting of C.S. Calude (Chair, Auckland), C. Ding (Hong Kong), M.J. Dinneen (Secretary, Auckland), M.R. Fellows (Victo- ria, Canada), M. Hallett (Zurich), M. Ito (Kyoto), S. Istrail (Rockville, USA), K-W. Lih (Taipei), S. Marcus (Bucharest), Y. Matiyasevich (St. Petersburg), Gh. Paun (Bucharest), S. Rudeanu (Bucharest), J. Rutten (Amsterdam), K.