ABACUS is a software system for the implementation of linear-programming based branch-and-bound algorithms, i.e., branch-and-cut algorithms, branch-and-price algorithms, and their combination. It applies the concepts of object oriented programming (programming language C++). An implementation of a problem specific algorithm is obtained by deriving some classes from abstract base classes of ABACUS in order to embed problem specific functions.
Based on our earlier work on non-object oriented branch-and-cut frameworks, Stefan Thienel developed ABACUS 1.0 in his PhD thesis that was defended in December 1995. Since January 1996 he developed the public releases ABACUS 1.2 to 2.1 with the partial support of ESPRIT LTR Project no. 20244 (ALCOM-IT) and H.C.M. Institutional Grant no. ERBCHBGCT940710 (DONET). Stefan Thienel laid the foundations of ABACUS with great dedication and enthusiasm. We regret that he decided to leave the Universität zu Köln in spring 1998. Very much to our satisfaction, Max Böhm and Thomas Christof immediately took over the responsibility for ABACUS. We are very glad that ABACUS is again in competent hands and future development and maintenance is guaranteed.
Köln, August 1998 Michael
Jünger
Heidelberg, August 1998 Gerhard
Reinelt
ABACUS 2.1 was left ready for release in February 1998 by Stefan Thienel. After Stefan Thienel left university and we took over the responsibility for ABACUS, we decided not to release ABACUS 2.1, but to add some new features to the software. The major enhancements of the resulting version 2.2 are the interface to the LP solver Xpress and the compilation of ABACUS with different native compilers. In addition, we introduced some new functions for easier parameter handling and improved the HTML version of the Reference Manual. A complete presentation of all modifications can be found in Section 3.3.
We are very grateful to Stefan Thienel for his efforts involved in the development, documentation and support of ABACUS, and wish him the very best for his future. For the users of ABACUS, we hope that this transition in responsibility will be almost invisible to them.
Köln, August 1998 Max
Böhm
Athens, GA, August 1998 Thomas
Christof