The search for higher homotopy Hopf algebras (known today as A∞-bialgebras) began in 1996 during a conference at Vassar College honoring Jim Stasheff in the year of his 60th birthday. In a talk entitled ”In Search of Higher Homotopy Hopf Algebras”, I indicated that a DG Hopf algebra could be thought of as some (unknown) higher homotopy structure with trivial higher order structure and deformed ...

In this paper we examine the stability of a class of simple three-dimensional point-mass hoppers, which have minimal feedback. These hoppers, with varying leg numbers, are representative of both animal and robotic runners: singlestance-leg runners such as humans, birds, and some monopod robots; double-stance-leg hoppers such as kangaroos; and triplestance-leg runners like the cockroach or the r...

Steganography is the science of hiding the very presence of a secret message within a public com-munication channel. In Crypto 2002, Hopper, Langford, and von Ahn proposed the first complexity-theoretic definition and constructions of stegosystems. They later pointed out a flaw in their basic con-struction. Their proposed fix for this flaw dramatically reduces the efficiency of ...

The article highlights the problems of ensuring continuous unloading energy willow cuttings from slotted bunkers. During free discharge rod-like bodies, such phenomena as crypt formations, distortions, pinching occur, which stop under action gravity. Finding parameters, system will work evenly and without stops, make it possible to automate many processes related working with material, in parti...