On the Cauchy problem and $T$-products for hypoelliptic systems

The Cauchy problem is studied for systems of pseudodifferential hypoelliptic equations. An existence and uniqueness theorem is established for the solution, the asymptotic behavior of the solution as $t\to0$ is examined, and various representations of the solution in the form of $T$-products of operators are studied.
Bibliography: 18 titles.