Abstract: SUB and COM are very important operators frequently used in reasoning network graphs of expert systems. AND and OR are the special cases of SUB and COM. The half scenery search method and the maximum superiority search method developed for searching ideal AND/OR graphs can be extended to searching ideal non-AND/OR graphs containing SUB and COM operators, and the maximum reliability search method for searching ideal AND/OR graphs is applicable to the non- ideal AND/OR graphs containing circuit structures.