Complex delay fault reasoning with sequential 7-valued algebra

A method is proposed for simulating of transition delay faults (TDF) at different fault propagation conditions. The main idea of the method is to extend the TDF model, traditionally considered as a class of robustly tested delay faults, to a class of TDFs with extended detection conditions like non-robust and functional sensitization. A new sensitization type, called nonrobust functional sensitization was introduced as well. A novel delay fault reasoning algorithm based on sequential 7-valued algebra is presented, which is used for fault coverage calculation separately for all mentioned four types of TDFs. By experimental results we established that the fault coverage share for different types of TDFs considerably depends on the quality of delay test.