Geometric Problems

1976 ◽  
pp. 157-162
Author(s):  
George Pólya ◽  
Gabor Szegö
Keyword(s):  
2021 ◽  
Vol 51 (4) ◽  
pp. 4-5
Author(s):  
Frederic Green

The three books reviewed in this column are about central ideas in algorithms, complexity, and geometry. The third one brings together topics from the first two by applying techniques of both property testing (the subject of the first book) and parameterized complexity (including its more focused incarnation studied in the second book, kernelization) to geometric problems.


OPSEARCH ◽  
1999 ◽  
Vol 36 (1) ◽  
pp. 42-50
Author(s):  
R. Chandrasekaran ◽  
Santosh N. Kabadi

1977 ◽  
Vol 8 (6) ◽  
pp. 662-704
Author(s):  
G. V. Kuz'mina

1976 ◽  
pp. 366-379
Author(s):  
George Pólya ◽  
Gabor Szegö
Keyword(s):  

1982 ◽  
Vol 11 (2) ◽  
pp. 217-226 ◽  
Author(s):  
Douglas Comer ◽  
Michael J. O’Donnell
Keyword(s):  

Author(s):  
Mihajlo Cekić ◽  
Thibault Lefeuvre

Abstract Given a smooth Hermitian vector bundle $\mathcal{E}$ over a closed Riemannian manifold $(M,g)$, we study generic properties of unitary connections $\nabla ^{\mathcal{E}}$ on the vector bundle $\mathcal{E}$. First of all, we show that twisted conformal Killing tensors (CKTs) are generically trivial when $\dim (M) \geq 3$, answering an open question of Guillarmou–Paternain–Salo–Uhlmann [ 14]. In negative curvature, it is known that the existence of twisted CKTs is the only obstruction to solving exactly the twisted cohomological equations, which may appear in various geometric problems such as the study of transparent connections. The main result of this paper says that these equations can be generically solved. As a by-product, we also obtain that the induced connection $\nabla ^{\textrm{End}({\operatorname{{\mathcal{E}}}})}$ on the endomorphism bundle $\textrm{End}({\operatorname{{\mathcal{E}}}})$ has generically trivial CKTs as long as $(M,g)$ has no nontrivial CKTs on its trivial line bundle. Eventually, we show that, under the additional assumption that $(M,g)$ is Anosov (i.e., the geodesic flow is Anosov on the unit tangent bundle), the connections are generically opaque, namely that generically there are no non-trivial subbundles of $\mathcal{E}$ that are preserved by parallel transport along geodesics. The proofs rely on the introduction of a new microlocal property for (pseudo)differential operators called operators of uniform divergence type, and on perturbative arguments from spectral theory (especially on the theory of Pollicott–Ruelle resonances in the Anosov case).


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