PrediCalc: A Logical Spreadsheet Management System

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PrediCalc A Logical Spreadsheet Management System
Stanford Logic Group
VLDB 2005 Demo

• Michael Kassoff
• Lee-Ming Zen
• Ankit Garg
• Michael Genesereth
• August 30, 2005

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Electronic Spreadsheets

• Huge success
• Used by everyone from multinational conglomerates
  to individuals
• Limitations
• Functional definitions
• Unidirectional update

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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

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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

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Features of PrediCalc

• 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(X) ? q(X)
p
q
a
a
p
q
b
b
User specified
System generated
p(X) ? r(X)
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Inconsistency Tolerance

• Uses a novel technique to handle inconsistency of
  values with constraints
• Gives users feedback about violated constraints
• (I cant explain this in 5 minutes see the demo!)

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Thanks!