Inference Engine

• Full name: ISI Mediator
• URL: http://www.isi.edu/info-agents/Prometheus/
• Source(s):
  • Name: ISI Information Agents Research Group
  • URL: http://www.isi.edu/info-agents/
• Inference Rule(s):
  • Name: Source Data Access
  • Description in English: This rule represents the result of a subquery executed againts a remote (or local) source. The subquery can range from a simple realtion scan to a complex SQL query.
  • Example in English: DataAccess(cdw, "laptop(processor, ram, hardrive, price, ...)") DataAccess(db1, "select x, y from R, S where R.y = S.y")
  • Source(s):
    • Name: A Relational Model of Data for Large Shared Data Banks
    • URL: http://www.acm.org/classics/nov95/
    • Author(s):
      • Name: Edgar F. Codd
      • URL: http://www.acm.org/awards/turing_citations/codd.html
    • Publisher:
      • Name: Association for Computing Machinery
      • URL: http://www.acm.org/
    • Year: 1970

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  • Name: Relational Algebra Join
  • Description in English: This rule represents the relational algebra (binary) join operator. It takes two input relations and a join expression and outputs a relation that is the subset of tuples in the cartesian product of the input relations that satify the join expression.
  • Example in English: Join("r(x, y)", "s(u, v)", "y = u", "j(x, y, u, v)") Join("r(x, y)", "s(u, v)", "x > u ^ y <= u", "j(x, y, u, v)")
  • Source(s):
    • Name: A Relational Model of Data for Large Shared Data Banks
    • URL: http://www.acm.org/classics/nov95/
    • Author(s):
      • Name: Edgar F. Codd
      • URL: http://www.acm.org/awards/turing_citations/codd.html
    • Publisher:
      • Name: Association for Computing Machinery
      • URL: http://www.acm.org/
    • Year: 1970

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  • Name: Relational Algebra Projection
  • Description in English: This rule represents the relational algebra projection operation. It output a new relation with only the specified columns.
  • Example in English: Project("r(x, y, z)", "x, y", "s(x, y)")
  • Source(s):
    • Name: A Relational Model of Data for Large Shared Data Banks
    • URL: http://www.acm.org/classics/nov95/
    • Author(s):
      • Name: Edgar F. Codd
      • URL: http://www.acm.org/awards/turing_citations/codd.html
    • Publisher:
      • Name: Association for Computing Machinery
      • URL: http://www.acm.org/
    • Year: 1970

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  • Name: Relational Algebra Selection
  • Description in English: This rule represents the relational algebra selection operator. It filters an input relation according to a selection expression, producing another relation.
  • Example in English: Select("r(x, y)", "x = 7", "s(x, y)") Select("r(x, y)", "x > y ^ y <= 3", "s(x, y)")
  • Source(s):
    • Name: A Relational Model of Data for Large Shared Data Banks
    • URL: http://www.acm.org/classics/nov95/
    • Author(s):
      • Name: Edgar F. Codd
      • URL: http://www.acm.org/awards/turing_citations/codd.html
    • Publisher:
      • Name: Association for Computing Machinery
      • URL: http://www.acm.org/
    • Year: 1970

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  • Name: Relation Algebra Multi-Relation Union
  • Description in English: This rule represents the relational algebra union operator. It accepts an arbitrary number of input relations and produces the union of the sets of tuples (removing duplicates).
  • Example in English: Union([r(x, y, z), s(x, y, z), t(x, y, z)], "u(x, y, z)")
  • Source(s):
    • Name: A Relational Model of Data for Large Shared Data Banks
    • URL: http://www.acm.org/classics/nov95/
    • Author(s):
      • Name: Edgar F. Codd
      • URL: http://www.acm.org/awards/turing_citations/codd.html
    • Publisher:
      • Name: Association for Computing Machinery
      • URL: http://www.acm.org/
    • Year: 1970

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