COMPUTATION-TUPLE SEQUENCES AND OBJECT HISTORIES

A record-based, algebraically-oriented model is introduced for describing data for 'object histories' (with computation), such as checking accounts, credit-card accounts, taxes, schedules, etc. The model consists of sequences of computation tuples defined by a computation-tuple sequence scheme (CSS). The CSS has three major features (in addition to input data): computation (involving previous computation tuples), 'uniform' constraints (whose satisfaction by a computation-tuple sequence u OVER BAR implies satisfaction by every interval of u OVER BAR ), and specific sequences with which to start the valid computation-tuple sequences. A special type of CSS, called 'local', is singled out for its relative simplicity in maintaining the validity of a computation-tuple sequence. A necessary and sufficient condition for a CSS to be equivalent to at least one local CSS is given. Finally, the notion of 'local bisimulatabilty' is introduced for regarding two CSS as conveying the same information, and two results on local bisimulatability in connection with local CSS are established.