books.google.com - This monograph contains exciting original mathematics that will inspire new directions of research in algebraic geometry. Developed here is an arithmetic analog of the theory of ordinary differential equations, where functions are replaced by integer numbers, the derivative operator is replaced by a...http://books.google.com/books/about/Arithmetic_Differential_Equations.html?id=aqwYKFjW5nwC&q=degree&utm_source=gb-gplus-shareArithmetic Differential Equations