Roger ChalkleyRoger Chalkley earned the degree of Ch.E. in 1954 at the University of Cincinnati where he earned an A.M. (mathematics) in 1956 and a Ph.D. (mathematics) in 1958. Since 1989, his research has focused on invariants for ordinary differential equations.To revive that truly interesting subject, it is advantageous to regard invariants as differential polynomials into which substitutions can be made. Then, as elements of a differential ring, they can be constructed in terms of simpler members. Read More Read Less