are not particularly noted for the pleasure which they give to their recipients. One meaning of the word dummy is a "counterfeit object." This seems to me the right word to describe a form of treatment which is intended to have no effect and I follow those who use it. A placebo is something which is intended to act through a psychological mechanism. It is an aid to therapeutic suggestion, but t...

We prove that every recursively enumerable language can be generated by a programmed grammar with context-free core rules using unconditional transfer with leftmost derivation of type 3 or type 2. We show that every recursively enumerable tally language can be generated by a programmed grammar with context-free core rules using unconditional transfer or by some k-limited ET0L system, where k 2 ...

We give a complete characterization of so called powerful arithmetic progressions, i.e. of progressions whose kth term is a kth power for all k. We also prove that the length of any primitive arithmetic progression of powers can be bounded both by any term of the progression different from 0 and ±1, and by its common difference. In particular, such a progression can have only finite length.

This paper suggests a exible framework for n-dimensional crossover, consisting of cutting, classi cation, and copying of genes. We prove that under this framework, any cutting strategy generates two equivalence classes of genes, making the framework appropriate as a crossover scheme. Three notable features of this framework are: (i) it enables more e ective use of genes' geographical linkage, (...

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Computing systems are often very hard for most people to approach. To some extent this is because of the inherent difficulty of giving machines the ability to communicate in ways which people find natural: not enough is understood about speech and how it is decoded, about the structure and functions of natural languages, about how the average person thinks about problems and processes. However ...

Biomolecular computers, along with quantum computers, may be a future alternative for traditional, silicon-based computers. Main advantages of biomolecular computers are massive parallel processing of data, expanded capacity of storing information and compatibility with living organisms (first attempts of using biomolecular computers in cancer therapy through blocking of improper genetic inform...

When proving invariance properties of programs one is faced with two problems. The rst problem is related to the necessity of proving tautologies of the considered assertion language, whereas the second manifests in the need of nding suuciently strong invariants. This paper focuses on the second problem and describes techniques for the automatic generation of invariants. The rst set of these te...