WHAT Those are a few programs to compute counts of polyominoes by following the technique of Redelmeier, D. H. ``Counting Polyominoes: Yet Another Attack.'' Discrete Math. 36, 191-203, 1981. Notice that Redelmeier's method is now superseeded by a much more efficient (and complex) method, which the page attributes to Tony Guttmann, Iwan Jensen (University of Melbourne) and Ling Heng Wong. (See also ) COMPILATION Just issue % make USAGE There are three programs. - simple.out , illustrates D. H. Redelmeier's algorithm for counting fixed polyominoes usage: ./simple.out [-v]* n, count fixed polyomoinoes of size n -v, show the polyominoes - fix.out, optimized program for counting fixed polyominos usage: ./fix.out [-r checkpointfile] [-o checkpointfile] [-v] n The argument checkpointfile is the name of a file, where the current state of the enumeration process will be saved from time to time. -r name, restart enumeration from the state in file name. -o name, save states into file name. -v output messages about saving and restoring states. - free.out counts free polyominoes. It first counts the polyominoes invariant by certain isometric transforms and then deduces the count of free polyominoes (see article). To perform the latter step, it reads the file fixes.txt that contains the counts of fixed polyominoes from 1 to 26. usage ./free.out [-v[pr]]* n -v, show all the invariant polyominoes -vp, show non-ring polyominoes -vr, show rings