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Axiomatizable class

(Redirected from Module (model theory))

In mathematics, an axiomatizable class is a class whose standard definition can be expressed as a sentence of formal symbols . The resulting sentences that can be built out of the axioms are the topic of study of model theory.

Thus, for example, the axiomatic sentences of a multiplicative group are:

\forall xyz \, \, (xy)z = x(yz)
\forall x\,\, x \cdot 1 = x
\forall x\,\, x \cdot x^{-1} = 1.

The axioms of a left R-module are the axioms of a multiplicative group, together with the additional sentences

\forall xy \,\, r(x+y)=r(x)+r(y) for all r\in R
\forall x \,\, (r+s)(x)=r(x)+s(x) for all r,s\in R
\forall x \,\, (rs)(x)=r(s(x)) for all r,s\in R
\forall x \,\, 1(x)=x.

Many of the common classes of mathematics are easily axiomatizable, including the rings, fields, lattices, boolean algebras and the like.

See also

References

  • Wilfrid Hodges (1997). A shorter model theory. Cambridge University Press. ISBN 0-521-58713-1.
Last updated: 05-08-2005 15:18:36
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