Instances of the 3-dimensional assignment problem
This page lists 18 files, each corresponding to an instance. These instances have been used for computational purposes in the paper: "Approximation algorithms for three-dimensional assignment problems with triangle inequalities", European Journal of Operational Research 60, 273-279 (1992) by Yves Crama and myself.

Let me shortly explain the setup. Consider Table 1 on page 279 of the EJOR-paper . There are 19 rows in this table, say 0,1,2,...,18. Each row in this table (except row 0) corresponds to an instance. Hereunder are the 18 file-names each of which contains a single instance. Notice that the i-th filename in this sequence corresponds to the instance described in row i of Table 1. Each file has the following structure: the first line contains a '3', the second line contains the value of n for the particular instance (so either 33 or 66), and next are the three matrices c_{IJ}, c_{IK} and c_{JK} (see the EJOR-paper), separated by an empty line.

Notice that the values in Table 1 in rows 1,2,...,12 should be multiplied by 100. (The reason that we presented these numbers is that in the description of the type 1 and type 2 problems (page 278) we mention that we generate randomly points in [0,1] \times [0,1]. We did this by first generating randomly integral points in [0,100] \times [0,100], solving the instance and then correcting for this by dividing by 100 again). All this holds, mutatis mutandis, for Table 2 as well.

If there remains anything unclear or if you experience difficulties getting these data, please let me know. Of course, I'm interested in anyone's results on these problems.

Instance -------- Optimal solution