@INPROCEEDINGS { Rsds2543,
author = {Kanda, Akira and Apostoli, Peter John}, 
title = {Upper and Lower Recursion Schemes in Abstract Approximation Spaces}, 
booktitle = {Rough Sets, Fuzzy Sets, Data Mining, and Granular Computing}, 
series =  = {Lecture Notes in Artificial Intelligence}, 
volume = 2639, 
pages = {205--212}, 
publisher = {Springer-Verlag}, 
address = {Heidelberg - Berlin, Germany}, 
month = {May}, 
year = 2003, 
editor = {Wang, Guoying and Liu, Quing and Yao, Yiyu and Skowron, Andrzej}, 
issn = {0302-9743}, 
isbn = {3-540-14040-9}, 
abstract = {An approximation space (U,R) placed in a type-lowering retraction with P(U x U) provides a model for a first order calculus of relations for computing over lists and reasoning about the resulting programs. Upper and lower approximations to the scheme of primitive recursion of the Theory of Pairs are derived from the approximation operators of an aaabstract approximation space.}, 
keywords = {natural deduction set theory, negation in logic programming systems, the second recursion theorem, rough sets, abstract approximation spaces and modal logic, }, 
}