In mathematics, obstruction theory is a name given to two different mathematical theories, both of which yield cohomological invariants. In the original...

In algebraic geometry, given a Deligne–Mumford stack X, a perfect obstruction theory for X consists of: a perfect two-term complex E = [ E − 1 → E 0 ]...

Measure theory — Model theory — Module theory — Morse theory — Nevanlinna theory — Number theory — Obstruction theory — Operator theory — Order theory — PCF...

Workers (Obstruction) Act 2006 Obstruction set in forbidden graph characterizations, in the study of graph minors in graph theory Obstruction theory, in mathematics...

In mathematics, homotopy theory is a systematic study of situations in which maps can come with homotopies between them. It originated as a topic in algebraic...

theory Obstruction theory Operator theory Order theory Percolation theory Perturbation theory Probability theory Proof theory Queue theory Ramsey theory Random...

mathematics. Fibrations are used, for example, in Postnikov systems or obstruction theory. In this article, all mappings are continuous mappings between topological...

studied, first by having a normal map from a manifold, and then via obstruction theory. Sometimes, Poincaré space means a homology sphere with non-trivial...

equivalence Hurewicz theorem H-space Künneth theorem De Rham cohomology Obstruction theory Characteristic class Chern class Chern–Simons form Pontryagin class...

1-skeleton a topological graph. The skeletons of a space are used in obstruction theory, to construct spectral sequences by means of filtrations, and generally...

assignment algorithm. A significant contribution in topology is his obstruction theory for the smoothing of homeomorphisms. These developments establish...

rectifiable. Instead of a limit argument, the proof is based on relative obstruction theory. This condition is open and dense in the space of all Jordan curves...

theory in its infancy in the 1930s (as part of obstruction theory) was one major reason why a 'dual' theory to homology was sought. The characteristic class...

X is a quasi-projective proper moduli scheme carrying a symmetric obstruction theory, then the weighted Euler characteristic χ ( X , ν X ) = ∑ n ∈ Z n...

surgery theory does not give a complete set of invariants to these questions. Instead, it is obstruction-theoretic: there is a primary obstruction, and a...

dimension 1 and 2, and by Edwin E. Moise in dimension 3. By using obstruction theory, Robion Kirby and Laurent C. Siebenmann were able to show that the...

The Five Obstructions is a 2003 Danish documentary film directed by Lars von Trier and Jørgen Leth. The film is conceived as a documentary, but incorporates...

determined by the perfect obstruction theory and s0! is the refined Gysin homomorphism defined just as in Fulton's "Intersection theory". The same paper shows...

non-holonomic solution is much easier to handle and can be addressed with the obstruction theory for topological bundles. While many underdetermined partial differential...

{\text{Ext}}^{1}({\mathcal {E}},{\mathcal {E}})^{\vee }} which gives a perfect obstruction theory of dimension 0. In particular, this implies the associated virtual...

cohomology operations still see modern usage, for example, in the obstruction theory of commutative ring spectra. Examples of secondary and higher cohomology...

topology. Her dissertation, Equivariant Wall Obstruction Theory, concerned Wall's finiteness obstruction, and was supervised by Douglas R. Anderson. After...

all manifolds, but their failure to be manifolds can be measured by obstruction theory. Bruhat decomposition Fundamental class Weyl group Hatcher, Allen...

January 30, 1998) was a Polish-American mathematician who co-founded category theory (with Saunders Mac Lane) and homological algebra. He was born in Warsaw...

then these choices may be extended over the two-skeleton, then (by obstruction theory) they may automatically be extended over all of M. In particle physics...

chains. It is also called the Moore complex. obstruction cocycle obstruction theory Obstruction theory is the collection of constructions and calculations...

Kummer as the main obstruction to the direct proof of Fermat's Last Theorem. From this beginning in the 1950s, a substantial theory has been built up....

Politeness theory, proposed by Penelope Brown and Stephen Levinson, centers on the notion of politeness, construed as efforts to redress the affronts to...

groups, which led to higher real K-theories. Together with Paul Goerss, Hopkins later set up a systematic obstruction theory for refinements to E ∞ {\displaystyle...

and examples (an important instance being Kai Behrend's symmetric obstruction theories); further together with Damien Calaque these authors introduced and...