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Symmetric product of genus 2-surface

Let $\Sigma$ be the genus 2-surface. Denote $\operatorname{Sym}^2(\Sigma)=\Sigma\times \Sigma/\mathbb{Z}/2$, where $\mathbb{Z}/2$ acts on $\Sigma\times \Sigma$ by $(x,y)\mapsto (y,x)$. In the very ...
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1answer
133 views

What's isotopy of framings?

I am reading R.E.Gompf and A.I. Stipsicz, 4-Manifolds and Kirby Calculus.At pp.100-101,the authors say "isotopy classes of framings."I don't know how to determine isotopy to framings.Please tell me ...