GSS

GSS - graph-structured stack is a directed acyclic graph where each directed path represents a stack. The graph-structured stack is an essential part of tomita's algorithm, where it replaces the usual stack of a pushdown automaton. This allows the algorithm to encode the nondeterministic choices in parsing an ambiguous grammar.

See:

• Graph-structured Stack and Natural Language Parsing (Tomita, ACL 1988)