Order-of-magnitude reasoning with O[M]

Michael L. Mavrovouniotis, George Stephanopoulos

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The O[M] formalism for Order-of-Magnitude reasoning is described. O[M] is based on seven primitive relations among absolute magnitudes of quantities: 'much less than' (< <), 'moderately less than' (- <), 'slightly less than' (∼ <), 'equal to' (= =), 'slightly greater than' (> ∼), 'moderately greater than' (> -), and 'much greater than' (> >). 21 compound relations are formed as implicit disjunctions of consecutive primitive relations. A strict interpretation of the relations allows exact conservative inferences, while a heuristic interpretation allows more aggressive and human-like inferences, by permitting some slack at each inference step. Inference strategies are based on propagation of order-of-magnitude relations through properties of the relations, algebraic constraints, and rules. O[M] operates mainly in the data-driven direction with assumption-based truth-maintenance for the resolution of contradictions. O[M] provides efficient integration of quantitative and qualitative knowledge in the expression and solution of engineering problems. The system has been applied in process engineering and biochemical engineering.

Original languageEnglish (US)
Pages (from-to)106-114
Number of pages9
JournalArtificial Intelligence in Engineering
Issue number3
StatePublished - Jul 1989
Externally publishedYes


  • approximate reasoning
  • approximate relation
  • approximation
  • artificial intelligence
  • order-of-magnitude reasoning
  • qualitative reasoning
  • relative magnitude
  • semiquantitative reasoning

ASJC Scopus subject areas

  • Computer Science(all)
  • Engineering(all)


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