Find a single Forth instruction set that works “out-of-the-box” in both primordial soup and long-tape settings

Determine whether there exists a Forth instruction set that, without special modifications, spontaneously yields self-replicators in both the tape-pairing “primordial soup” setting and the single long-tape setting used in the paper.

Background

The paper explores Forth in two distinct environments: (1) a primordial soup where fixed-size tapes interact via concatenation, and (2) a long tape setting where interpreters execute overlapping code regions. While replicators emerge in both, the authors had to use different instruction sets for each environment.

This unresolved issue concerns whether a unified, minimal Forth instruction set can serve both environments and still support spontaneous replicator emergence without seeding or tailored modifications.

References

Despite self-replicators emerging in both of these settings, we didn't find an instruction set that works “out-of-the-box” for both settings.

— Computational Life: How Well-formed, Self-replicating Programs Emerge from Simple Interaction (2406.19108 - Arcas et al., 27 Jun 2024) in Section 4, Subsection “Forth” (introductory paragraph)