RTXPS
Reference &
User Manual
    RTXPS  On-line Reference Manual

      Release Level 2.0
      Release Date 2012 06
      Revision Level 1.0
    Last modified on:   Saturday, 11-Aug-12 22:26 CEST

    Forward chaining RULES

    The forward chaingin RULES are very similar to the first order production rules used in the backward chaining version of the expert system, XPS.

    The main difference is the action or consequence part: while in the backward chaining branch, this is always an ASSIGNMENT setting the value of a DESCRIPTOR, each forward chaining RULE executes one or more from a repertoir of FUNCTIONS in its concequence part.

    Basic RULE syntax and logic

    RTXPS uses basid production RULES in forst order logic.

    The generic RULE syntax is:

      IF   CONDITION1 
           AND/OR CONDITION 2
            .....
           AND/OR CONDITION i
      THEN ACTION 1
      [optional]
           AND ACTION 2
            .....
           AND ACTION i
      [optional]
      ELSE ACTION a
      [optional]
           AND  ACTION  b
            .....
           AND  ACTION j
      

      where   CONDITION is short for CONDITION = TRUE, and a construct of the form:

          IF TRUE   (unconditionally true, will always execute)
        
          IF function()   arbitrary function call, using DESCRIPTORs as arguments
             or uses the dynamic Knowledge Base for its context/input,
             that returns TRUE or FALSE
        
          IF DESCRIPTOR OPERATOR VALUE (direct comparison/evaluation see below, 
           or triggering  backward chaining inference tree of arbitrary nesting 
           and number of RULES; alternative METHODS/branches and optional defaults guarantee 
           completion of the inference even with limited/lacking data)
        
      where OPERATOR can be any one of the basic first logic operators:  =,   ≠,   >,   ≥,   <   ≤ .

      Please note that the final ELSE clause as well as AND in the consequence part of a RULE is optional.

      The forward chaining RULES can be edited and managed with an interactive web-based tool, the RTXPS rule editor.

    Data base structure

    • RULES, condition part

      mysql> describe rule_cond; function
      FieldTypeNull Key Default Description
      id int(11) NO PRI 0
      seq int(11) NO PRI 0
      ifandor varchar(255) YES NULL AND or OR clause
      parup int(11) YES NULL open parenthesis
      varchar(255) YES NULL
      descriptor varchar(255) YES NULL
      operator varchar(255) YES NULL
      operand varchar(255) YES NULL
      pardown int(11) YES NULL close parenthesis

    • RULES, action part

      mysql> describe rule_act;
      FieldTypeNull Key Default Description
      id int(11) NO PRI 0
      seq int(11) NO PRI 0
      function varchar(255) YES NULL
      descriptor varchar(255) YES NULL
      operator varchar(255) YES NULL
      operand varchar(255) YES NULL


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