Technical Note—Clustering a Data Array and the Traveling-Salesman Problem

A clustering of a nonnegative M×N array is obtained by permuting its rows and columns. W. T. McCormick et al. [Opns. Res. 20, 993–1009 (1972)] measure the effectiveness of a clustering by the sum of all products of nearest-neighbor elements in the permuted array. This note points out that this clustering problem can be stated as two traveling-salesman problems.