e/Pebble automaton

Information
has gloss	eng: In information science, a pebble automaton is an extension of tree walking automata which allows the automaton to use a finite amount of "pebbles", used for marking tree node. The result is a model stronger than ordinary tree walking automata, but still strictly weaker than branching automata.
lexicalization	eng: pebble automaton
instance of	e/Tree (data structure)