Information Hiding and the Complexity of Constraint Satisfaction

This paper discusses the complexity of constraint satisfaction, and the effect of information hiding. On the one hand, powerful constraint satisfaction is necessarily global, and tends to break information hiding. On the other hand, preserving strict information hiding increases the complexity of constraint satisfaction, or severely limits the power of the constraint solver. Ultimately, under strict information hiding, constraint satisfaction on complex objects cannot be guaranteed

Interval Computations on the Spreadsheet

This paper reviews work on using interval arithmetic as the basis for next generation spreadsheet programs capable of dealing with rounding errors, imprecise data, and numerical constraints. A series of ever more versatile computational models for spreadsheets are presented beginning from classical interval arithmetic and ending up with interval constraint satisfaction. In order to demonstrate the ideas, an actual implementation of each model as a class library is presented and its integration with a commercial spreadsheet program is explained. 1 LIMITATIONS OF SPREADSHEET COMPUTING Spreadsheet programs, such as MS Excel, Quattro Pro, Lotus 1--2--3, etc., are among the most widely used applications of computer science. Since the pioneering days of VisiCalc and others, spreadsheet programs have been enhanced immensely with new features. However, the underlying computational paradigm of evaluating arithmetical functions by using ordinary machine arithmetic has remained the same. The wor..