Scindement d’une équivalence d’homotopie en dimension
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Harrie Hendriks, François Laudenbach (1974)
Annales scientifiques de l'École Normale Supérieure
E. Dror, W.G. Dwyer, D.M. Kann (1981)
Commentarii mathematici Helvetici
B. J. Ball (1974)
Colloquium Mathematicae
Yoav Segev (1994)
Mathematische Zeitschrift
Greg Friedman (2007)
Fundamenta Mathematicae
We show that there exist non-trivial piecewise linear (PL) knots with isolated singularities , n ≥ 5, whose complements have the homotopy type of a circle. This is in contrast to the case of smooth, PL locally flat, and topological locally flat knots, for which it is known that if the complement has the homotopy type of a circle, then the knot is trivial.
Karol Borsuk (1976)
Fundamenta Mathematicae
Willi Meier (1983)
Mathematische Zeitschrift
Jan Spaliński (2003)
Fundamenta Mathematicae
The fourth axiom of a model category states that given a commutative square of maps, say i: A → B, g: B → Y, f: A → X, and p: X → Y such that gi = pf, if i is a cofibration, p a fibration and either i or p is a weak equivalence, then a lifting (i.e. a map h: B → X such that ph = g and hi = f) exists. We show that for many model categories the two conditions that either i or p above is a weak equivalence can be embedded in an infinite number of conditions which imply the existence of a lifting (roughly,...
Csorba, Péter (2009)
The Electronic Journal of Combinatorics [electronic only]
M. Aubry, Jean-Michel Lemaire (1991)
Annales de l'institut Fourier
On sait qu’il y a 144 classes d’homotopies d’applications de dans lui-même dont la restriction à est homotope à l’identité: ce sont des exemples d’applications qui induisent l’identité en homologie et en homotopie. Plus généralement, soit un complexe de Poincaré 1-connexe de dimension , qui n’a pas le type d’homotopie rationnelle de : si est formel, nous montrons que le groupe des classes d’homotopies d’applications de dans , dont la restriction au -squelette est homotope à l’identité,...
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