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Stanford Logic Group VLDB 2005 Demo. PrediCalc: A Logical Spreadsheet Management System. Michael Kassoff Lee-Ming Zen Ankit Garg Michael Genesereth August 30, 2005. Electronic Spreadsheets. Huge success
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Stanford Logic Group VLDB 2005 Demo PrediCalc: A Logical Spreadsheet Management System Michael Kassoff Lee-Ming Zen Ankit Garg Michael Genesereth August 30, 2005
Electronic Spreadsheets • Huge success • Used by everyone from multinational conglomerates to individuals • Limitations • Functional definitions • Unidirectional update
From Functions to Constraints Generalizing formulae to many-to-many constraints allows us to use spreadsheets for a wide variety of applications • Correct-on-capture data entry (smart forms) • “Start times must be before end times” • “The number of lap infants traveling must not be greater than the number of adults” • Enterprise Management policies • “Only senior managers can reserve the third floor conference room” • Design / Configuration • “Students must take at least 2 math courses to graduate”
Logical Spreadsheets We choose to represent many-to-many relationships using logical formulae start-time(S) and end-time(E) before(S,E) “The start time must be before the end time” event-owner(O) and senior-manager(O) event-room(room301) “Only senior managers can reserve the third floor conference room” The focus is on symbolic data rather than numeric data
Features of PrediCalc p(X) q(X) • Distinguishes between user-specified cells and computed cells • Computed cells contain logical consequences of user-specified cells • Allows for simple retraction of value assignments • Propagation can occur in any direction • Constraints are not independent: p(X) q(X) q(X) r(X) p q a a p q b b User specified System generated p(X) r(X)
Inconsistency Tolerance • Uses a novel technique to handle inconsistency of values with constraints • Gives users feedback about violated constraints (I can’t explain this in 5 minutes… see the demo!)