Don Coppersmith
IEEE Trans. Inf. Theory
An animal A is a set of unit squares in the plane, parallel to the axes, and with corners at integer lattice points. We show that any animal A with four cells tiles the plane, in the sense that infinitely many copies of A, translated by integer vectors and possibly rotated through 90°, 180°, or 270°, can be placed so as to fill plane exactly without overlap. © 1985.
Don Coppersmith
IEEE Trans. Inf. Theory
Richard Arratia, Béla Bollobás, et al.
Discrete Applied Mathematics
Don Coppersmith, Uriel Feige, et al.
SIAM Journal on Discrete Mathematics
Inder S. Gopal, Don Coppersmith, et al.
IEEE TC