Thank you for explanations! But one problem is still not clear.
>> 4. The notion of constructability refers to a non-evolving TM
>> with a fixed program, but LTTT refers to evolution. Then how can we
>> speak about constructability of TMs that pass the LTTT?
>
>We can't. The whole point of the paper is that (evolving) machines that
>passed the LTTT are not constructable! (or to be more precise the
>initial TM might be constructable but the final one after training might
>not).
No, you did not understand my point. I was saying that the
notion of constructibility is not relevant for describing
evolving TMs. I believe that these are 2 different statements:
1. Evolving TMs (that pass the LTTT) are not constructable.
2. The notion of constructability is not applicable to evolving TMs.
My impression is that the latter statement is more correct.
A fly may be wingless but an elephant can not be wingless
because the notion of wing is not applicable. It looks like
"non-constructability" is not a quality in the same way as
being "non-existent" is not a quality.
-Alexei
-------------------------------------------------
Alexei Sharov Research Scientist
Dept. of Entomology, Virginia Tech, Blacksburg, VA 24061
Tel. (540) 231-7316; FAX (540) 231-9131; e-mail sharov@vt.edu
Home page: http://www.gypsymoth.ento.vt.edu/~sharov/alexei.html