Kang, M. H., H. Dietz, and B. Bhargava, "Multiple-query Optimization
at Algorithm-level", Data & Knowledge Engineering Journal, Vol. 14,
pp. 57-75, Elsevier Science B.V.. 

<blockquote> 
The database multiple-query optimization can be achieved
by analyzing multiple-query sequences at a level below that used by
current optimizers, but above the low-level executable code.  In this
paper, the concept of the "algorithm-level" representation of a
database program is defined and optimization techniques that can be
applied to the algorithm-level representation are discussed.  Some
techniques extend existing concepts, while others are new.  In this
paper, we also show multiple-query optimization can be performed
across the update queries.  
</blockquote>