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<a accesskey="3" href="page.php?w=homotopy_groups_of_spheres&amp;p=2">3.Next</a>
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<p><a href="page.php?w=Image%3ASphere_wrapped_round_itself.png">right</a>In the <a href="page.php?w=mathematics">mathematical</a> field of <a href="page.php?w=algebraic_topology">algebraic topology</a>, the <b>homotopy groups of spheres</b> describe how spheres of various <a href="page.php?w=Dimension">dimension</a>s can wrap around each other. They are examples of <a href="page.php?w=topological_invariant">topological invariant</a>s, which reflect, in <a href="page.php?w=abstract_algebra">algebraic</a> terms, the structure of spheres viewed as</p><p>
<a accesskey="3" href="page.php?w=homotopy_groups_of_spheres&amp;p=2">3.Next</a>
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