| Input: Legal Pattern Database LPD, Fraud Pattern Database FPD, Incoming Transaction , |
| Number of costumers “”, Number of attributes “”, matching percentage “mp” |
| Output: 0 (if legal) or 1 (if fraud) |
| Assumption: |
| (1) First attribute of each record in pattern databases and incoming transaction is Customer ID |
| (2) If an attribute is missing in the frequent itemset (ie, this attribute has different values in |
| each transaction and thus it is not contributing to the pattern) then we considered it as invalid. |
| Begin |
| lc = 0; //legal attribute match count |
| fc = 0; //fraud attribute match count |
| for = 1 to do |
| if (LPD(, 1) = (1)) then //First attribute |
| for = 2 to do |
| if (LPD() is valid and LPD() = ()) then |
| lc = lc + 1; |
| endif |
| endfor |
| endif |
| endfor |
| for = 1 to do |
| if (FPD() = (1)) then |
| for = 2 to do |
| if (FPD() is valid and FPD() = ()) then |
| fc = fc + 1; |
| endif |
| endfor |
| endif |
| endfor |
| if (fc = 0) then //no fraud pattern |
| if ((lc/no. of valid attributes in legal pattern) ≥ mp) then |
| return (0); //legal transaction |
| else return (1); //fraud transaction |
| endif |
| elseif (lc = 0) then //no legal pattern |
| if ((fc/no. of valid attributes in fraud pattern) ≥ mp) then |
| return (1); //fraud transaction |
| else return (0); //legal transaction |
| endif |
| elseif (lc > 0 && fc > 0) then //both legal and fraud |
| patterns are available |
| if (fc ≥ lc) then return (1); //fraud transaction |
| else return (0); //legal Transaction |
| endif |
| endif |
| End |
