Is the set of partitions of a given length, say $n$, of the unit interval compact?
2026-03-27 03:59:09.1774583949
Set of finite partitions of the unit interval
49 Views Asked by Bumbble Comm https://math.techqa.club/user/bumbble-comm/detail At
1
There are 1 best solutions below
Related Questions in COMPACTNESS
- Every nonempty perfect set in $\mathbb R^k$ is uncountable: Rudin's argument
- Help in understanding proof of Heine-Borel Theorem from Simmons
- Is the distance between those compact sets equal to $0$?
- Are compact groups acting on Polish spaces essentially Polish?
- Set of Positive Sequences that Sum to 1 is Compact under Product Topology?
- The space $D(A^\infty)$
- Proving the one-point compactification of a topological space is a topology
- Never Used Compact Closure...
- Continuity of the maximal element of a multi-valued function
- Consider the metric space of infinite sequences of 0s and 1s under this metric.
Related Questions in SET-PARTITION
- Existence of a denumerble partition.
- Given N sets of partitions, find a partition such that it satisfies a criterion
- Given a decreasing family of sets and partitions with a refinement condition, is there a monotonous choice function from the partitions?
- Partition of an $n$-element set such that the smallest component has at least $k$ elements?
- Number of equivalence relations on a set with $kn$ elements with the condition that each equivalence class has n elements
- Is there a similar notion of cycle type commonly in use for finite partitions, where instead of cycle sizes one counts the block sizes?
- Is it possible to construct two subsequences of a sequence X with specific properties such that the two subsequence sums are the same?
- Coloring $\mathbb{R}^2$ and single-colored paths
- A homework problem about set theory
- Canonical name for the partition that a partition of a set induces on its subsets
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?
I subsequently realized that it is not compact.
First of all, let us think of a partition of length $n$ as a vector of length $n$ with given endpoints: $0$ and $1$. Therefore a partition is a vector of length $n-2$, of points chosen from $(0,1)$, ordered from lowest to highest. Therefore the set of all such partitions, $S \subset (0,1)^{n-2}$, is bounded.
But it is not closed because it is easy to show that there exist sequences of such partitions which collapse on to $(0,0,...,1,1)$ in the limit, which is a degenerate partition (i.e. not a partition of length $n$). For example, suppose $n$ is even and consider the sequence of partitions $\{(\frac{1}{N},\frac{2}{N},...,\frac{(n-2)}{2N},\frac{N-\frac{n-2}{2}}{N},...,\frac{(N-2)}{N},\frac{(N-1)}{N})\}^{\infty}_{N=10}$, which collapses on to $(0,0,...,1,1)$ in the limit. Similarly it is easy to show for odd $n$ as well.
However, following the above logic, the set of all finite partitions of $[0,1]$ upto length $n$ is a compact set.