This volume presents the proceedings of the 20th International Workshop on Graph-Theoretic Concepts in Computer Science (WG '94), held in Herrsching, Germany in June 1994.
The volume contains 32 thoroughly revised papers selected from 66 submissions and provides an up-to-date snapshot of the research performed in the field. The topics addressed are graph grammars, treewidth, special graph classes, algorithms on graphs, broadcasting and architecture, planar graphs and related problems, and special graph problems.

After a pause taken in 2008 (owed to the political situation in the Caucasus region where CASC 2008 was supposed to take place), CASC 2009 continued the series of international workshops on the latest advances and trends both in the methods of computer algebra and in applications of computer algebra systems (CASs) to the solution of various problems in scienti?c computing. The ten earlier CASC conferences, CASC 1998, CASC 1999, CASC 2000, CASC2001, CASC2002, CASC2003, CASC2004, CASC2005, CASC2006, and CASC 2007 were held, respectively, in St. Petersburg (Russia), in Munich (G- many),...