The papers in this volume were presented at SWAT'94, the Fourth Scandinavian Workshop on Algorithm Theory. The workshop, which is really a conference, continues the tradition of SWAT'88, SWAT'90 and SWAT'92, and of the Workshops on Algorithms and Data Structures (WADS'89, WADS'91 and WADS'93), and is intended as an international forum for researchers in the area of design and analysis of algorithms. The SWAT conferences are coordinated by the SWAT steering committee, which consists of B. Aspvall (Bergen), S. Carlsson (Lulea), H. Hafsteinsson (Reykjavik), R. Karlsson (Lund), A. Lingas (Lund), E. M. Schmidt (Aarhus) and E. Ukkonen (Helsinki).