## 3 Results
### DL Query Interface  
The results shown in Figures 3-10 may not be so intuitive to users not directly involved in cancer registration, but Protege also includes a DL query interface for framing specific queries on the reasoned knowledge base. In addition, with the OWL application programme interface (OWL-API [29]), it is possible to tailor the output of the reasoner (or even swap out the reasoner with programme logic) along the lines shown in Figure A7 of Appendix C and discussed further in Section 4. Figures 11-17 show four examples of DL queries with the reasoner-provided explanations for the inferences. They may be crosschecked with the outputs illustrated in Figure A7. The DL query in Figure 11 is to find all entities having at least one duplicate primary tumour, c.f. Axioms (3) and (6). Three patients were found corresponding to p1, p4, and p5. Figure 12 shows the explanation provided by the reasoner for the case of patient p1 (which is in effect the situation depicted in Figure 5), where it has been found that:  
* one of the topography codes C768 in the tumour couplet is in the group common to all other topography groups and therefore a duplicate topography group condition, c.f. Axiom (4) and lines 5, 15, and 1 in Figure 12;
* the morphology codes in the tumour couplet are identical since there is only one morphology code and therefore a duplicate morphology condition, c.f. Axiom (7) and lines 2, 14, and 13 in Figure 12;
* the tumour couplet p1_tc3 is a duplicate tumour since it has both a duplicate topography condition as well as a duplicate morphology condition, c.f. Axiom (6) and line 7 in Figure 12;
* Finally, since p1 has a tumour couplet p1_tc3 (line 9 in Figure 12) and the tumour couplet is a duplicate primary tumour, p1 is one of the entities found by the DL query specified in Figure 11.  
Figure 11: Results of a DL query for entities that have duplicate primary tumours. The DL query in Figure 13 is to ascertain entities with haematoligical morphologies in a common group (which should automatically flag a duplicate primary tumour, c.f. Figure 1). The reasoner-provided explanation for returning the result of the tumour couplet p5_tc1 is shown in Figure 14.  
Figure 12: Explanation provided by the reasoner concerning why patient p1 has a tumour couplet that is a duplicate primary tumour. Figure 13: DL query for tumour couplets with haematological morphologies in a common group. The reasoner has found one such case-p5_tc1, with the explanation provided in Figure 14.  
Figure 15 is DL query for all entities having both a duplicate morphology group condition and a duplicate topography group condition (one of the other triggers for a primary multiple tumour, c.f. Figure 1). The reasoner found the two tumour couplelets: p1_tc3 and p4_tc1 (c.f. Figures 5 and 9, and Figure 10). The explanation behind p1_tc3 is provided in Figure 16.  
Figure 14: Explanation provided by the reasoner for the result of the DL query in Figure 13. Lines 8 and 16 reveal that the two morphologies in the couplet belong to the TcellNKcellNeoplasm category and therefore trigger the duplicate morphology group condition (line 6). Line 9 reveals that both morphologies are classified as haematogical morphologies. This set of conditions serves to flag the duplicate primary tumour condition of p5_tc1 in the related Figure 10, c.f. Axiom (3). Figure 15: DL query for entities with both a duplicate topography and a duplicate morphology condition (one of the triggers for a multiple primary tumour). In Figure 16, the reasoner has ascertained in lines 16 and 15 that there is only one morphology (i.e., the morphology codes are the same in both tumours of the tumour coupler). In lines 1, 13, 6, 7, and 3 the reasoner has ascertained that the conjunction of topographies C269 and C768 automatically triggers a duplicate topography group condition, c.f. Axiom (5). The final example in Figure 17 shows the results of a DL query on all entities having exactly one morphology.