Aspects include identifying, for a set of decision rules, one or more decision rules missing from the set of decision rules, the one or more missing decision rules satisfying a set of limitations. A decision rule determines whether a decision is made for a case, and a limitation determines the cases for which a decision should be made. A constraint graph that represents the cases for which no rule of the set of rules makes a decision, and for which all limitations of the set of limitations are satisfied, is built. A missing case represented by the constraint graph is created, and a family description is created from the missing case. The family description is a set of cases for which no rule of the set of rules makes a decision. The one or more missing decision rules are then constructed from the family description.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A computer-implemented method of identifying, for a set of decision rules, one or more decision rules missing from the set of decision rules, the one or more missing decision rules satisfying a set of limitations, wherein a decision rule determines whether a decision is made for a case, and wherein a limitation determines the cases for which a decision should be made, comprising: receiving the set of decision rules; receiving the set of limitations; building a constraint graph that represents the cases for which no rule of the set of rules makes a decision, and for which all limitations of the set of limitations are satisfied; constructing a missing case represented by the constraint graph; constructing a family description from the missing case, wherein the family description represents a set of cases for which no rule of the set of rules makes a decision and for which all limitations of the set of limitations are satisfied; and constructing the one or more missing decision rules from the family description. 2. A computer-implemented method as claimed in claim 1, wherein building the constraint graph comprises: building a ruleset inhibition graph that represents the cases for which no rule of the set of rules makes a decision; and building a limitation satisfaction graph that represents the cases for which a limitation of the set of limitations is satisfied; and wherein the constraint graph is built from a conjunction of the ruleset inhibition graph and the limitation satisfaction graph. 3. A computer-implemented method as claimed in claim 2, wherein the missing case is constructed from the constraint graph by determining a labelling of the constraint graph that satisfies operations of the graph nodes. 4. A computer-implemented method as claimed in claim 1, wherein the family description is constructed from logical tests that occur in the rules of the set of rules, and logical tests that occur in the limitations of the set limitations, that are satisfied by the missing case. 5. A computer-implemented method as claimed in claim 1, wherein constructing the missing decision rule from the family description comprises: building a ruleset applicability graph that represents the cases for which a rule of the set of rules makes a decision; building a limitation violation graph that represents the cases for which no limitation of the set of limitations is satisfied; and building a second constraint graph from the disjunction of the ruleset inhibition graph and the limitation satisfaction graph. 6. A computer-implemented method as claimed in claim 5, wherein the missing decision rule is constructed from the family description by selecting the logical tests of the family description for which no case that satisfies all the logical tests satisfies the second constraint graph. 7. A computer-implemented method as claimed in claim 6, wherein the logical tests of the family description are selected in reverse order of generality. 8. A computer-implemented method as claimed in claim 1, wherein the method is repeated until no further missing decision rules are identified. 9. A computer system for identifying, for a set of decision rules, one or more decision rules missing from the set of decision rules, the one or more missing decision rules satisfying a set of limitations, wherein a decision rule determines whether a decision is made for a case, and wherein a limitation determines the cases for which a decision should be made, wherein the computer system comprises memory and a processor system and is arranged to: receive the set of decision rules, and store them in the memory; receive the set of limitations, and store them in the memory; use the processor system to build a constraint graph that represents the cases for which no rule of the set of rules makes a decision, and for which all limitations of the set of limitations are satisfied; use the processor system to construct a missing case represented by the constraint graph; use the processor system to construct a family description from the missing case, wherein the family description represents a set of cases for which no rule of the set of rules makes a decision and for which all limitations of the set of limitations are satisfied; and use the processor system to construct the one or more missing decision rules from the family description. 10. A computer system as claimed in claim 9, arranged to build the constraint graph by: building a ruleset inhibition graph that represents the cases for which no rule of the set of rules makes a decision; and building a limitation satisfaction graph that represents the cases for which a limitation of the set of limitations is satisfied; and wherein it is further arranged to build the constraint graph from a conjunction of the ruleset inhibition graph and the limitation satisfaction graph. 11. A computer system as claimed in claim 10, arranged to construct the missing case from the constraint graph by determining a labelling of the constraint graph that satisfies operations of the graph nodes. 12. A computer system as claimed in claim 9, arranged to construct the family description from logical tests that occur in the rules of the set of rules, and logical tests that occur in the limitations of the set limitations, that are satisfied by the missing case. 13. A computer system as claimed in claim 9, arranged to construct the missing decision rule from the family description by: building a ruleset applicability graph that represents the cases for which a rule of the set of rules makes a decision; building a limitation violation graph that represents the cases for which no limitation of the set of limitations is satisfied; and building a second constraint graph from the disjunction of the ruleset inhibition graph and the limitation satisfaction graph. 14. A computer system as claimed in claim 13, arranged to construct the missing decision rule from the family description by selecting the logical tests of the family description for which no case which satisfies all the logical tests satisfies the second constraint graph. 15. A computer system as claimed in claim 14, arranged to select the logical tests of the family description in reverse order of generality. 16. A computer system as claimed in claim 9, arranged to repeat identifying missing decisions until no further missing decision rules are identified. 17. A computer program product for identifying, for a set of decision rules, one or more decision rules missing from the set of decision rules, the one or more missing decision rules satisfying a set of limitations, wherein a decision rule determines whether a decision is made for a case, and wherein a limitation determines the cases for which a decision should be made, the computer program product comprising a computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code configured to perform: receiving the set of decision rules; receiving the set of limitations; building a constraint graph that represents the cases for which no rule of the set of rules makes a decision, and for which all limitations of the set of limitations are satisfied; constructing a missing case represented by the constraint graph; constructing a family description from the missing case, wherein the family description represents a set of cases for which no rule of the set of rules makes a decision and for which all limitations of the set of limitations are satisfied; and constructing the one or more missing decision rules from the family description. 18. A computer program product as claimed in claim 17, wherein building the constraint graph comprises: building a ruleset inhibition graph that represents the cases for which no rule of the set of rules makes a decision; and building a limitation satisfaction graph that represents the cases for which a limitation of the set of limitations is satisfied; and wherein the constraint graph is built from a conjunction of the ruleset inhibition graph and the limitation satisfaction graph. 19. A computer program product as claimed in claim 17, wherein constructing the missing decision rule from the family description comprises: building a ruleset applicability graph that represents the cases for which a rule of the set of rules makes a decision; building a limitation violation graph that represents the cases for which no limitation of the set of limitations is satisfied; and building a second constraint graph from the disjunction of the ruleset inhibition graph and the limitation satisfaction graph. 20. A computer program product as claimed in claim 19, wherein the missing decision rule is constructed from the family description by selecting the logical tests of the family description for which no case that satisfies all the logical tests satisfies the second constraint graph.