Let G be a torsion-free group and G' a group of finite index. Suppose G' has finite cohomological dimension. Then it has a finite-dimensional K(G',1) complex. Its universal cover X' is also finite-dimensional, and it is a contractible free G'-complex. What can we do to construct a finite-dimensional, contractible free G-complex from X'? What I am reading says that X, as a set, can be defined as Hom$_{G'}(G,X')$, but I don't really see this. This is in the context of Serre's theorem about virtual cohomological dimension.
2026-03-28 22:35:49.1774737349
constructing a universal cover from K(G,1) space
113 Views Asked by Bumbble Comm https://math.techqa.club/user/bumbble-comm/detail AtRelated Questions in ALGEBRAIC-TOPOLOGY
- How to compute homology group of $S^1 \times S^n$
- the degree of a map from $S^2$ to $S^2$
- Show $f$ and $g$ are both homeomorphism mapping of $T^2$ but $f$ is not homotopy equivalent with $g.$
- Chain homotopy on linear chains: confusion from Hatcher's book
- Compute Thom and Euler class
- Are these cycles boundaries?
- a problem related with path lifting property
- Bott and Tu exercise 6.5 - Reducing the structure group of a vector bundle to $O(n)$
- Cohomology groups of a torus minus a finite number of disjoint open disks
- CW-structure on $S^n$ and orientations
Related Questions in GROUP-COHOMOLOGY
- Group cohomology of $\mathrm{GL}(V)$
- How to compute group cohomology $H^2_\sigma(\mathbb{Z}\times \mathbb{Z}, \mathbb{Z}_2\times \mathbb{Z}_2)$ with nontrivial $G$-module
- Cohomological Interpretation of Modular Forms on a Modular Curve
- Group cohomology with the coefficient $\frac{1}{n}\mathbb{Z}/\mathbb{Z}$
- A $G$-module admits a surjection from a $G$-module, which is free as an abelian group, such that the kernel is free
- Different constructions of group homology
- What is the pushout of $D^n \longleftarrow S^{n-1} \longrightarrow D^n$?
- Group theoretic interpretation of the cohomology of $K(G, n)$
- Action of a group on set of morphisms
- Crossed homomorphism/derivation on free group
Trending Questions
- Induction on the number of equations
- How to convince a math teacher of this simple and obvious fact?
- Find $E[XY|Y+Z=1 ]$
- Refuting the Anti-Cantor Cranks
- What are imaginary numbers?
- Determine the adjoint of $\tilde Q(x)$ for $\tilde Q(x)u:=(Qu)(x)$ where $Q:U→L^2(Ω,ℝ^d$ is a Hilbert-Schmidt operator and $U$ is a Hilbert space
- Why does this innovative method of subtraction from a third grader always work?
- How do we know that the number $1$ is not equal to the number $-1$?
- What are the Implications of having VΩ as a model for a theory?
- Defining a Galois Field based on primitive element versus polynomial?
- Can't find the relationship between two columns of numbers. Please Help
- Is computer science a branch of mathematics?
- Is there a bijection of $\mathbb{R}^n$ with itself such that the forward map is connected but the inverse is not?
- Identification of a quadrilateral as a trapezoid, rectangle, or square
- Generator of inertia group in function field extension
Popular # Hahtags
second-order-logic
numerical-methods
puzzle
logic
probability
number-theory
winding-number
real-analysis
integration
calculus
complex-analysis
sequences-and-series
proof-writing
set-theory
functions
homotopy-theory
elementary-number-theory
ordinary-differential-equations
circles
derivatives
game-theory
definite-integrals
elementary-set-theory
limits
multivariable-calculus
geometry
algebraic-number-theory
proof-verification
partial-derivative
algebra-precalculus
Popular Questions
- What is the integral of 1/x?
- How many squares actually ARE in this picture? Is this a trick question with no right answer?
- Is a matrix multiplied with its transpose something special?
- What is the difference between independent and mutually exclusive events?
- Visually stunning math concepts which are easy to explain
- taylor series of $\ln(1+x)$?
- How to tell if a set of vectors spans a space?
- Calculus question taking derivative to find horizontal tangent line
- How to determine if a function is one-to-one?
- Determine if vectors are linearly independent
- What does it mean to have a determinant equal to zero?
- Is this Batman equation for real?
- How to find perpendicular vector to another vector?
- How to find mean and median from histogram
- How many sides does a circle have?