Our algorithm actually only needs one (packed) subtree for several ( X, q) E Ui,k with fixed X,i,k but different q. The resulting parse forests would then be optimally compact, contrary to some other LR-based tabular algorithms, as pointed out by Rekers (1992), Nederhof (1993) and Nederhof (1994b).
This has been investigated before by Nederhof (1994a, p. 25) and Villemonte de la Clergerie (1993, p. 155).
The conceptual simplicity of our formulation of tabular LR parsing allows comparison with other tabular parsing techniques, such as Earley's algorithm (Earley, 1970) and tabular left-corner parsing (Nederhof, 1993), based on implementationindependent criteria.
(See also Lang (1974), Villemonte de la Clergerie (1993) and Nederhof (1994a), and for LR parsing specifically gipps (1991) and Leermakers (19925)).
3As remarked before by Nederhof (1993), the algorithms by Schabes (1991) and Leermakers (1989) are not really related to LR parsing, although some notation used in these papers suggests otherwise.