Bradley, James2008-02-272008-02-271994-05-01http://hdl.handle.net/1880/46310An extended relational algebra has been developed. This extended algebra is suitable for reduction of expressions written in the object-oriented 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 tupple could have been joined to an R2 tuple, otherwise p false. Generalized algebra routines for generalized COOL expressions are presented.EngComputer Scienceunknown1994-540-0910.11575/PRISM/30437