Examples of constraint adding and constraint removal. Some interesting references to systems with views. In an incremental system user commands would be retained after execution, forming a document, or a solution, much like a batch main program. Such a tool might take over the burden of interaction from the applications programmer, do it better and produce documented answers. Interactivity generally means two things - immediate execution and response, and solution of problems by trial and error.
Solution is the process by which an answer is produced.
An ideal incremental system performs only the computations necessary to bring the previous answers into agreement with the new version of the program. The paper explores different ways to analyze incremental algorithms. Rather than express the cost of the incremental computation as a function of the size of the current input, the cost is measured in terms of the sum of the sizes of the changes in the input and the output. The existence of a non-incremental problem is shown. Only attribute instances affected in a changed tree are reevaluated.