Christer Kiselman: Characterizing digital straightness using the chord property, word combinatorics, Diophantine inequalities, and difference operators

The notion of digital straightness has been studied since Azriel Rosenfeld’s seminal paper of 1974 . In particular, characterizations using the chord property, word combinatorics, and double Diophantine inequalities have been investigated. To these I will add characterizations using difference operators and show how these four aspects relate to each other. If time permits, I will also discuss the related, more general notion of digital convexity — as is to be expected, convexity and concavity jointly is equivalent to straightness.