A spreadsheet based on constraints

Constraints allow the user to declare relationships among objects and let the system maintain and satisfy these relationships. This paper is concerned with the design of a spreadsheet based on constraints. Instead of formulas, we let the user enter numerical constraints, such as >, c and = over the real values in the cells of the spreadsheet. Recalculating the spreadsheet then means (1) checking whether the given cellvalues satisfy all constraints and (2) finding values for cells that satisfy the constraints.