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• CommentRowNumber1.
• CommentAuthorUrs
• CommentTimeApr 10th 2014

some basics at congruence subgroup

• CommentRowNumber2.
• CommentAuthorUrs
• CommentTimeApr 22nd 2014

added a paragraph Relation to spin strutcures on elliptic curves on how over the complex numbers the congruence subgroup $\Gamma_0(2)$ is the one that fixes the “NS-R” spin strutcure on the elliptic curve.