Undecidability of the positive \(\forall\exists^ 3\)-theory of a free semigroup (Q1921846)
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scientific article; zbMATH DE number 923560
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | Undecidability of the positive \(\forall\exists^ 3\)-theory of a free semigroup |
scientific article; zbMATH DE number 923560 |
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Undecidability of the positive \(\forall\exists^ 3\)-theory of a free semigroup (English)
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8 January 1997
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Let \(\Pi_n\) denote a free semigroup of rank \(n\) with free generators \(a_1,\dots,a_n\). The main result is Theorem 1. For \(n\geq 2\) the positive \(\forall\exists^3\)-theory of \(\Pi_n\) is algorithmically undecidable.
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free semigroups
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free generators
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positive \(\forall\exists^ 3\)-theory
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algorithmically undecidable theories
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