| 1: | app(g,app(h,app(g,x))) | → app(g,x) | |
| 2: | app(g,app(g,x)) | → app(g,app(h,app(g,x))) | |
| 3: | app(h,app(h,x)) | → app(h,app(app(f,app(h,x)),x)) | |
| 4: | APP(g,app(g,x)) | → APP(g,app(h,app(g,x))) | |
| 5: | APP(g,app(g,x)) | → APP(h,app(g,x)) | |
| 6: | APP(h,app(h,x)) | → APP(h,app(app(f,app(h,x)),x)) | |
| 7: | APP(h,app(h,x)) | → APP(app(f,app(h,x)),x) | |
| 8: | APP(h,app(h,x)) | → APP(f,app(h,x)) | |