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We prove the following four results on communication complexity: 1) For every k ≥ 2, the language L<subscrpt>k</subscrpt> of encodings of directed graphs of out degree one that contain a path of length k+1 from the first vertex to the last vertex and can be recognized by exchanging O(k log n) bits using a simple k-round protocol requires exchanging… (More)
We prove the following lower bounds for <underline>on line</underline> computation. 1) Simulating two tape <underline>nondeterministic</underline> machines by one tape machines requires Ω(n log log n) time. 2) Simulating k tape (deterministic) machines by machines with k pushdown stores requires Ω(n log<supscrpt>1/(k+1)</supscrpt>n) time.
It is known that k tapes are no better than two tapes for nondeterministic machines. We show here that two tapes are better than one. In fact, we show that two pushdown stores are better than one tape. Also, k tapes are no better than two for nondeterministic reversal-bounded machines. We show here that two tapes are better than one for such machines. In… (More)
We introduce new techniques for deriving lower bounds on the message complexity in asynchronous distributed computation. These techniques combine the choice of specific patterns of communication delays and crossing sequence arguments with consideration of the speed of propagation of messages, together with careful counting of messages in different parts of… (More)
A specific immunological approach was developed to enable acetylcholine (ACh) to be visualized in biological tissues. A variety of ACh-like immunogens were synthesized, and injected into rabbits. Antibody specificity was tested using an enzyme-linked immunosorbent assay (ELISA) method. The most immunoreactive ACh derivative was found to be… (More)