muzik wrote: are corderships actually considered engineered?
My answer is definitely yes. Even if they can occur in soup with high probability, yet they were found by using simpler components and "logical manipulations" with those components, they by definition engineered. This is why Gosper gun is engineered in my opinion.
Seems like a reasonable argument. Coming at it from a slightly different direction: Corderships are built out of natural puffers -- not the bare switch engine per se, but block-laying and glider-producing switch engines show up in C1 soups very regularly. So while they may be engineered, they're much less engineered than other types of macro-spaceships.
Is it worth having different terminology for minimally-engineered (Cordership), moderately-engineered (Caterpillar), and maximally-engineered (Demonoid) objects? The current distinction between "engineered" and "engineerable"
seems a little too subtle, when it's really trying to distinguish "non-adjustable" vs. "adjustable".
What I've been using for the last several years is "engineered" for stuff like the various Corderships, high-period rakes, and so on... but then "self-supporting" for the Caterpillar, Centipede, HBKs, and waterbear, and "self-constructing" for any object that carries around a construction recipe for itself. Caterpillars and HBKs and so on don't contain their own construction recipe -- the positions of the pi climbers or the half-bakeries or whatever aren't encoded anywhere. They do the work of closing the cycle so that the pi climbers can keep climbing indefinitely, or the half-bakeries will continue to get activated by the right gliders... but the spaceship as a whole is definitely not self-constructing.
But you could convert a Demonoid glider stream into, say, a stream of loafers, and feed it into a completely different-looking loafer-based replicator unit, and it would still construct a Demonoid replicator unit. The construction data is important, but the particular encoding is irrelevant.
simsim314 wrote:Another point is that in my view symmetric soups should also be included in the definition natural objects, like the symmetrical ships are considered "elementary" although they're symmetrical (and symmetry is definitely a "designed" feature in those ships). Symmetry is natural feature.
People have been pretty consistent about calling symmetric-soup objects like the pufferfish "almost natural". Really big areas of perfect symmetry happen very-nearly-never in random soup, so there is
something highly artificial about starting with a symmetric soup. But yes, the products of symmetric soup are still elementary and not engineered.