Imagine winding the hour hand of a clock back from 3 o’clock to noon. Mathematicians have long known how to describe this rotation as a simple multiplication: A number representing the initial ...

For q > 0 let A denote the unital ∗-algebra with generator x and defining relation xx* = qx*x. Based on this algebra we study q-normal operators and the complex q-moment problem. Among other things, ...