Baum–Connes conjecture
Can the proper-action geometry of a countable discrete group recover the K-theory of its reduced operator algebra?
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Can the proper-action geometry of a countable discrete group recover the K-theory of its reduced operator algebra?
Does the arithmetic fundamental group of a curve identify exactly its rational points?
Can an algorithm decide whether one database query always produces each answer no more often than another?
How widely does the fastest travel time vary across a square grid with independent random edge times?
Can smooth three-dimensional collisionless plasma equations develop a singularity from regular initial data?
Can every finite simple graph color its vertices and edges together using at most two colors beyond its maximum degree?
Must a region in a nonpositively curved space have at least the boundary area of a Euclidean ball with the same volume?
Does numerical nonnegativity of a minimal model’s canonical divisor guarantee a globally defined geometric map?
What is the largest disk radius guaranteed on a one-to-one image patch of every normalized holomorphic map?
Can a basic reversible cohomology operation on a complex algebraic variety always be reversed using algebraic cycles?
Must all entire complex curves in a general-type projective variety lie in one proper algebraic subset?
Can an algorithm decide whether an integer sequence defined by a linear recurrence never becomes negative?
Can a deterministic parallel algorithm find a perfect matching in every general graph with polylogarithmic time and polynomially many processors?
Can local changes control the fluctuations of functions under log-concave probability laws with a constant independent of dimension?
Does every separable nuclear C*-algebra satisfy the universal coefficient theorem relating its K-theoretic invariants?
Does every contractible two-dimensional polyhedron become collapsible after taking its product with one interval?
How much smoothing of a spherical frequency cutoff guarantees bounded Fourier reconstruction in higher dimensions?
Can all triangles in any finite simple graph be destroyed by removing at most twice its maximum number of edge-disjoint triangles?
Does every finite multipartite uniform hypergraph have a vertex cover at most r−1 times its largest matching?
Do separate allowed-color lists on edges always need no more colors than ordinary edge coloring?
How far can averaged control of prime-counting errors in arithmetic progressions extend as the modulus grows?
Can algebraic invariants of every group be assembled from its virtually cyclic subgroups?
Can finite groups detect every nontrivial element of every hyperbolic group?
Does a hyperbolic group whose boundary is a two-sphere act geometrically on hyperbolic three-space?