The lists of the automatic evaluation of every GRF with arity 0 and size from 2‒9 are:
For size 2 and 3, the only non‐terminating functions evaluate M(S), which is caught by my evaluator. For size 4, there are evaluations of the form M(C(S, _)), also caught by my evaluator. But those are the only forms my evaluator can detect itself, and there’s one infinite loop that’s not of either form: M⁰(C¹(P¹(1), S¹)). Fortunately, its non‐termination is obvious.
For size 5, there are 13 undetected infinite loops, which I manually evaluated here.
For size 6, I introduced pruning of functions which could be simplified to known non‐terminating functions, which left only 37 to manually validate here.
I then made the simplifier handle Cᵏ(Z, ...) ≡ Zᵏ and C(Pᵐ(i), g₁, ..., gₘ) ≡ gᵢ. This pruned the size 7 hold‐outs to 31 functions, evaluated here.