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On the first-order logic of terms

Published online by Cambridge University Press:  12 March 2014

Lars Svenonius*
Affiliation:
University of Maryland, College Park, Maryland 20742

Extract

By an elementary condition in the variablesx1, …, xn, we mean a conjunction of the form x1 ≤ i < jnaij where each aij is one of the formulas xi = xj or xixj. (We should add that the formula x1 = x1 should be regarded as an elementary condition in the one variable x1.)

Clearly, according to this definition, some elementary conditions are inconsistent, some are consistent. For instance (in the variables x1, x2, x3) the conjunction x1 = x2 & x1 = x3 & x2x3 is inconsistent.

By an elementary combinatorial function (ex. function) we mean any function which can be given a definition of the form

where E1(x1, …, xn), …, Ek(x1, …, xn) is an enumeration of all consistent elementary conditions in x1, …, xn, and all the numbers d1, …, dk are among 1, …, n.

Examples. (1) The identity function is the only 1-ary e.c. function.

(2) A useful 3-ary e.c. function will be called J. The definition is

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1973

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References

REFERENCES

[1]Furth, Montgomery, “Editor's Introduction” in Fregc's, G.The basic laws of arithmetic, translated and edited, with an introduction, by Furth, M., University of California Press, Berkeley, Calif., 1964.Google Scholar
[2]Hermes, H., Eine Termlogik mit Auswahloperator, Lecture Notes in Mathematics, vol. 6, Springer-Verlag, New York, 1965.Google Scholar
[3]Kanger, S., Provability in logic, Almquist and Wiksell, Stockholm, 1957.Google Scholar
[4]Kleene, S. C., Mathematical logic, Wiley, New York, 1967.Google Scholar