Bradley, James2008-02-272008-02-271993-07-01http://hdl.handle.net/1880/46308An extended relational algebra has been developed. This extended algebra is suitable for reduction of expressions written in the natural quantifier language COOL. The algebra consists of conventional operations plus a group select, a subgroup select and possibility join operation. The group select operation selects each group of related tuples where a quantity of the group obeys a condition. The subgroup-select operation selects each group of related tuples where a quantity of a subgroup of the group obeys a condition. The possibility join of relation R1 with relation R2 regenerates relation R1 but with each tuple having a logical attribute p concatenated, with p true where the R1 tuple could have been joined to an R2 tuple, otherwise p false. Generalized algebra routines for generalized COOL expressions are presented.EngComputer Scienceunknown1993-521-26http://dx.doi.org/10.11575/PRISM/30438