Obituaries

Roger Chalkley was born on June 21, 1931 in Cincinnati, Ohio. However, for all but a few years of his life, he lived near the Beechwood School in Fort Mitchell, Kentucky.

He was a student at Beechwood from kindergarten through his high school graduation in 1949. At the University of Cincinnati, he was awarded the Ch.E. degree in Chemical Engineering in 1954, the A.M. in Mathematics in 1956, and the Ph.D. in Mathematics in 1958. His father, Curtis Rathbone Chalkley, had earned the M.E. degree in Mechanical Engineering at the University of Cincinnati in 1914 as one of the earliest participants in Dean Herman Schneider's cooperative education program.

Roger Chalkley returned to the University of Cincinnati in 1962 as a member of the graduate faculty in the Department of Mathematics and has been employed there since that time. His primary area of research has been differential equations. From 1987 through 2005, he had the pleasure of completely redeveloping a remarkably interesting area of mathematics. In particular, he discovered simple explicit formulas for all of the basic global relative invariants for homogeneous linear differential equations as well as simple formulas for all those of numerous classes of nonlinear differential equations. Previously, only a few isolated relative invariants had been found before 1889 and no additional ones had been found between 1889 and 1987. His results about this were published in two Memoirs of the American Mathematical Society; the one appearing in 2002 has 204 pages and the more recent one consists of 365 pages. Among his other interests were teaching, natural history, and golf.

He was preceded in death by his parents, Curtis & Dorothy Chalkley.