  The Cayley-Dickson loop Q_n is the multiplicative closure of basic elements
of the algebra constructed by n applications of the Cayley-Dickson doubling
process (the first few examples of such algebras are real numbers, complex
numbers, quaternions, octonions, sedenions). We discuss properties of the
Cayley-Dickson loops, show that these loops are Hamiltonian, and describe the
structure of their automorphism groups.
