Improved solutions for some minimal-network test problems

In a recent SIGMAP newsletter [1] J. Soukup and W. F. Chow proposed forty-six test problems for the "Problem fo Steiner": finding the shortest network which connects a given set of points. All of the problems were planar, and except for one 62-point set (#11), the number of points per problem ranged from 3 to 20. Soukup and Chow also provided for each problem the length of the shortest network known to them, and they asserted the optimality of 24 of their solutions, including all eleven of the three-and four-point problems.