The Knowlton-Graham partition problem

A set partition technique that is useful for identifying wires in cables can be recast in the language of 0--1 matrices, thereby resolving an open problem stated by R.~L. Graham in Volume 1 of this journal. The proof involves a construction of 0--1 matrices having row and column sums without gaps

A note on digitized angles

We study the configurations of pixels that occur when two digitized straight lines meet each other