A 
-action or
-action. A
cascade and a single map 
are essentially the same, but the term "cascade"
is preferred by many Russian authors.
Cascade
See also
Action, FlowExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Cascade." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Cascade.html