flex Examples - LPIS

10 The Flex Example SuiteThe following descriptions provide a quick guide into which technical points arecovered by each example.SOLVENT.KSLThis example recommends a solvent to be used on some equipment. The solventrecommended depends on the equipment class, the ventilation of the site, the mainmaterial of the equipment and whether the equipment contains rubber compounds.The following additional flex technical points are demonstrated in this example:• The use of a single backward chaining relation to find the solvent.• The automatic asking of a question when its value is tested.• The use of square brackets to limit "or" disjunctions.BLOCKS.KSLThis example implements the blocks world problem, as defined in 'Logic for ProblemSolving' by Professor Robert Kowalski.The following additional flex technical points are demonstrated in this example:• The use of a single forward chaining rule to generate valid moves.• The use of square brackets in conjunction with "or".SPECIES.KSLThe objective of this example is to show two contrasting methods, forward andbackward chaining, for identifying a species of animal given a set of attributes.The following additional flex technical points are demonstrated in this example:• Disjunctions ("or") used in the conditions of a forward-chaining rule.• The constraining of a backward-chaining relation to a single solution.QUESTION.KSLThis simple example shows the range of different built-in questions that can be asked.The following additional flex technical points are demonstrated in this example:• The "do" directive for automatically running goals on compilation.• User-defined questions implemented in Prolog.• The catchall question that handles any undefined question asked.• The use of relations to constrain the answers to questions.A Guide to the Flex Expert System Toolkit