Semigroup generation propertiesof streaming operators with noncontractive boundary conditions

We present c0–semigroup generation results for the free streaming operator with abstract boundary conditions. We recall some known results on the matter and establish a general theorem (already announced in [1]). We motivate our study with a lot of examples and show that our result applies to the physical cases of Maxwell boundary conditions in the kinetic theory of gases as well as to the non—local boundary conditions involved in transport–like equations from population dynamics.