August 3, 1989

Dear Andrei Petrovich!

Thank you for the invitation to Urgench symposium. The truth is that I has not contemplate
successful realization of Nikolai Aleksandrovich’ plan to readdress his invitation to me. For
different reasons I should like very much N.A. to be able to participate in this symposium – my
interests may not be taken into account.

To be on the safe side, let me try to outline the topics among those mentioned in “The topics for
discussion” to which I could make some contribution (not pretending to make a separate talk). I
could describe a problem statement such that a single task becomes “algorithmically insoluble” or
“has a high lower complexity bound” – it concerns the topic 3. With respect to topic 1 I could speak
about algebraization of the notion of computation, having in mind algebraization seemingly
necessary for the progress in computational complexity estimates. Besides, I am very attracted by
your additional topic (concerning a course in algorithms and logics and invariant definition of
computation process).

…

With the hope to meet you in Urgench,

Yours A.O. Slisenko