Families of Two-Point Touching Squares
This Demonstration shows two-point touching families of squares. The number of squares and the tilt angle can be varied.
A family is said to be -touching provided each element of has a nonempty intersection with exactly other elements of . A -touching family is said to be point--touching if any two touching sets have only a single common point .
 B. Grünbaum, "Families of Point-Touching Squares," Geombinatorics, 12(4), 2003 pp. 167–174.