Two function algebras defining functions in NCk boolean circuits
We describe the functions computed by boolean circuits in NCk by means of functions algebra for k≥1 in the spirit of implicit computational complexity. The whole hierarchy defines NC. In other words, we give a recursion-theoretic characterization of the complexity classes NCk for k≥1 without referen...
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| Published in: | Information and computation Vol. 248; pp. 82 - 103 |
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| Main Authors: | , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier Inc
01.06.2016
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| Subjects: | |
| ISSN: | 0890-5401, 1090-2651 |
| Online Access: | Get full text |
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| Summary: | We describe the functions computed by boolean circuits in NCk by means of functions algebra for k≥1 in the spirit of implicit computational complexity. The whole hierarchy defines NC. In other words, we give a recursion-theoretic characterization of the complexity classes NCk for k≥1 without reference to a machine model, nor explicit bounds in the recursion schema. Actually, we give two equivalent descriptions of the classes NCk, k≥1. One is based on a tree structure à la Leivant, the other is based on words. This latter puts into light the role of computation of pointers in circuit complexity. We show that transducers are a key concept for pointer evaluation. |
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| ISSN: | 0890-5401 1090-2651 |
| DOI: | 10.1016/j.ic.2015.12.009 |