cyclic homotopy
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Homotopy groups of spheres — In the mathematical field of algebraic topology, the homotopy groups of spheres describe how spheres of various dimensions can wrap around each other. They are examples of topological invariants, which reflect, in algebraic terms, the structure… … Wikipedia
Cyclic category — In mathematics, the cyclic category or cycle category or category of cycles is a category of finite cyclically ordered sets and degree 1 maps between them. It was introduced by Connes (1983). Contents 1 Definition 2 Properties 3 Cyclic sets … Wikipedia
Hopf invariant — In mathematics, in particular in algebraic topology, the Hopf invariant is a homotopy invariant of certain maps between spheres. toc Motivation In 1931 Heinz Hopf used Clifford parallels to construct the Hopf map etacolon S^3 o S^2, and proved… … Wikipedia
Orthogonal group — Group theory Group theory … Wikipedia
Classifying space — In mathematics, specifically in homotopy theory, a classifying space BG of a topological group G is the quotient of a weakly contractible space EG (i.e. a topological space for which all its homotopy groups are trivial) by a free action of G. It… … Wikipedia
J-homomorphism — In mathematics, the J homomorphism is a mapping from the homotopy groups of the special orthogonal groups to the homotopy groups of spheres, defined by George W. Whitehead.The original homomorphism is defined geometrically, and gives a… … Wikipedia
Spherical 3-manifold — In mathematics, a spherical 3 manifold M is a 3 manifold of the form M = S3 / Γ where Γ is a finite subgroup of SO(4) acting freely by rotations on the 3 sphere S3. All such manifolds are prime, orientable, and closed. Spherical 3 manifolds are… … Wikipedia
Exotic sphere — In differential topology, a mathematical discipline, an exotic sphere is a differentiable manifold M that is homeomorphic but not diffeomorphic to the standard Euclidean n sphere. That is, M is a sphere from the point of view of all its… … Wikipedia
Projective unitary group — In mathematics, the projective unitary group PU( n ) is the quotient of the unitary group U( n ) by the right multiplication of its center, U(1), embedded as scalars.Abstractly, it is the isometry group of complex projective space, just as the… … Wikipedia
Mapping class group — In mathematics, in the sub field of geometric topology, the mapping class group is an important algebraic invariant of a topological space. Briefly, the mapping class group is a discrete group of symmetries of the space. Contents 1 Motivation 2… … Wikipedia
Whitehead torsion — In mathematics, Whitehead torsion is an invariant of an h cobordism in a Whitehead group, that is important in simple homotopy theory and surgery theory. It is named for J. H. C. Whitehead.Whitehead torsionSuppose that W is an h cobordism from M… … Wikipedia