Hi, I am evaluating Drool Gunvor for to implement Rules for some finance related functionality. I need help from users to implement following scenario is Drools-Guvnor I have created simple Rule to Calculate  House Rent Allowance i.e. HRA as    HRA = 0.12 * Basic salary .(Basic will come as Input Parameter). This rule is valid from e.g. 01-Jan-2005 to 31-July-2010 as HRA rule is changed from 1st Aug 2010 I will have to create new Rule for HRA Rule with new formula as HRA = 0.15 * Basic salary .(Basic will come as Input Parameter). This rule is valid from 01-Aug-2010 to 01-Aug-2999 From 1st Aug HRA should be calculated using New Rule. But at the same time if any Arrears to be calculated(back dated calculation) depending on the date old HRA rule should be applicable.I would need this to calculate Arrears i.e. doing backdated calculations Can I achieve this in Gunor Drool. I could achieve first half by specifying date-expires . But I am not able to achieve second half i.e. referring old rule depending on the date. I would appreciate help to solve this problem . Thanks in advance. Regards Minal S ________________________________ This Email may contain confidential or privileged information for the intended recipient (s) If you are not the intended recipient, please do not use or disseminate the information, notify the sender and delete it from your system. ______________________________________________________________________ _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users