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Ian Agol
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A pretzel link has as many components as the pretzel link with coefficients reduced $(\mod 2)$. So it will have two components if and only if there are precisely two even coefficients.

A conceptual classification is given by considering the 2-fold branched cover, or the $\pi$-orbifold, obtained by taking the orbifold quotient of the 2-fold branched cover. For pretzel links, the 2-fold branched cover is a connect sum of Seifert fibered spaces (this is more generally true for Montesinos links). Then thea 2-component link is trivial if and only if the two-fold branched cover is $S^2\times S^1 \\# S^2\times S^1$$S^2\times S^1$. A theorem of Bonahon and Siebenmann classifies Seifert fibered orbifolds, so in principal you can classify pretzel links from their classification.

A pretzel link has as many components as the pretzel link with coefficients reduced $(\mod 2)$. So it will have two components if and only if there are precisely two even coefficients.

A conceptual classification is given by considering the 2-fold branched cover, or the $\pi$-orbifold, obtained by taking the orbifold quotient of the 2-fold branched cover. For pretzel links, the 2-fold branched cover is a connect sum of Seifert fibered spaces (this is more generally true for Montesinos links). Then the link is trivial if and only if the two-fold branched cover is $S^2\times S^1 \\# S^2\times S^1$. A theorem of Bonahon and Siebenmann classifies Seifert fibered orbifolds, so in principal you can classify pretzel links from their classification.

A pretzel link has as many components as the pretzel link with coefficients reduced $(\mod 2)$. So it will have two components if and only if there are precisely two even coefficients.

A conceptual classification is given by considering the 2-fold branched cover, or the $\pi$-orbifold, obtained by taking the orbifold quotient of the 2-fold branched cover. For pretzel links, the 2-fold branched cover is a connect sum of Seifert fibered spaces (this is more generally true for Montesinos links). Then a 2-component link is trivial if and only if the two-fold branched cover is $S^2\times S^1$. A theorem of Bonahon and Siebenmann classifies Seifert fibered orbifolds, so in principal you can classify pretzel links from their classification.

Source Link
Ian Agol
  • 68.8k
  • 3
  • 194
  • 358

A pretzel link has as many components as the pretzel link with coefficients reduced $(\mod 2)$. So it will have two components if and only if there are precisely two even coefficients.

A conceptual classification is given by considering the 2-fold branched cover, or the $\pi$-orbifold, obtained by taking the orbifold quotient of the 2-fold branched cover. For pretzel links, the 2-fold branched cover is a connect sum of Seifert fibered spaces (this is more generally true for Montesinos links). Then the link is trivial if and only if the two-fold branched cover is $S^2\times S^1 \\# S^2\times S^1$. A theorem of Bonahon and Siebenmann classifies Seifert fibered orbifolds, so in principal you can classify pretzel links from their classification.