A list of NPO problems

The list contains more than 200 entries. A typical entry consists of eight parts: the first four parts are mandatory while the last four parts are optional.

1. The problem name that also specifies the goal of the problem.
2. The definition of the instances of the problem.
3. The definition of the feasible solutions of the problem.
4. The definition of the measure of a feasible solution.
5. A `good news' part that contains the best approximation result for the problem.
6. A `bad news' part that contains the worst approximation negative result for the problem.
7. A section of additional comments.
8. A reference to the `closest' problem appearing in the list published in [ 121 ].

The list is organized according to subject matter as done in [ 121 ]. In particular the entries are divided into the following twelve categories:

GT

Graph theory A : 51 entries.

ND

Network design B : 59 entries.

SP

Sets and partitions C : 11 entries.

SR

Storage and retrieval D : 10 entries.

SS

Sequencing and scheduling E : 20 entries.

MP

Mathematical programming F : 17 entries.

AN

Algebra and number theory G : 1 entry.

GP

Games and puzzles H : 2 entry.

LO

Logic I : 13 entries.

AL

Automata and language theory J : 5 entries.

PO

Program optimization K : 1 entry.

MS

Miscellaneous L : 14 entries.

We have ignored problems with too obscure definitions and problems for which the membership in NP was not guaranteed.