1. Dominance Fault Collapsing
Ravi Chandra Paruchuri
Spring 2004

2. Definition
If all tests of fault F2 detect another fault F1, then F2 is said to dominate F1.
In summary,
The n-input boolean gate requires n+1 single stuck at faults to be modeled
To collapse faults of a gate , all faults from the output can be eliminated retaining one type of fault (sa0 for AND and NAND; sa1 for OR and NOR) on each input and the other type on any one of the inputs
The output faults of the NOT gate and the wire can be removed as long as both faults on the input are retained
No collapsing is possible for fan out

3. Algorithm
Reads the .eqf file and picks up one fault from each line and stores it in a file say .txt file
Reads the number of inputs from .lev file
Retain all the faults from the primary inputs
Drop the fault if its on the output line
Pick the fault if its not on any primary input or on any output line
If the fault is 0 (.int file) and the gates (.lev file) are either AND or NAND, see whether the other inputs have a fan out or not . If the other input doesn’t have fan out drop the fault else retain all the faults
Similarly, if the fault is 1 and the gates are either OR or NOR see whether the other inputs have a fan out or not. If the other input doesn’t have fan out drop the fault else retain all the faults

5. All the results have been verified
The number of faults in the dominance collapsed set is 16 as compared to 22 of the equivalent collapsed set for circuit C17.
The number of faults in the dominance collapsed set is 248 as compared to 301 of the equivalent collapsed set for the circuit 74181(ALU with NAND gates)
All the results have been verified

6. Demo !!!!

7. Questions????