Categories
Tags
Examples-counterexamples
New post in Examples-counterexamples
Would the following NFA accept all strings?
February 28th, 2020
proof-writing
automata
examples-counterexamples
A sequence for which the set of limits points is the interval $[0,1]$.
August 1st, 2022
sequences-and-series
real-analysis
examples-counterexamples
Is there a bounded function discontinuous on a countable dense subset?
August 1st, 2022
real-analysis
examples-counterexamples
Counterexample in Fubini's Theorem (non-integrable function)
August 1st, 2022
lebesgue-integral
measure-theory
integration
real-analysis
examples-counterexamples
If $f: X \to Y$ is continuous and $E \subseteq X$ is closed and bounded, $f(E)$ is closed and bounded?
March 12th, 2020
general-topology
examples-counterexamples
real-analysis
Limit point Compactness does not imply compactness counter-example
August 1st, 2022
examples-counterexamples
intuition
general-topology
If $f_n$ converges uniformly to $f$ on a measure space, show integral of $f_n$ converges to integral of $f$.
August 1st, 2022
examples-counterexamples
measure-theory
integration
convergence-divergence
real-analysis
Double complex with exact rows
July 22nd, 2020
homological-algebra
examples-counterexamples
homology-cohomology
Example of decreasing sequence of sets with first set having infinite measure
August 1st, 2022
measure-theory
lebesgue-measure
examples-counterexamples
real-analysis
A completely regular topological space which is $T_0$ but not $T_1$?
June 5th, 2020
general-topology
separation-axioms
examples-counterexamples
Examples of product of two $L^1_\text{loc}$ functions that is not $L^1_{\text{loc}}$
August 1st, 2022
real-analysis
examples-counterexamples
functional-analysis
Intersection of clopen sets that contain x is the connected component of x (if X is compact)
September 17th, 2020
connectedness
general-topology
compactness
examples-counterexamples
Analytic Function with positive integers as zeros?
October 7th, 2020
complex-analysis
examples-counterexamples
Example of a Problem Made Easier with Skew Coordinates
August 1st, 2022
coordinate-systems
big-list
examples-counterexamples
Examples of a quotient map not closed and quotient space not Hausdorff
August 1st, 2022
examples-counterexamples
general-topology
separation-axioms
quotient-spaces
Is $f(A)\cap f(B)$ a subset of $f(A\cap B)$?
August 1st, 2022
functions
elementary-set-theory
examples-counterexamples
Continuity and interior
October 19th, 2020
examples-counterexamples
general-topology
continuity
Example of $\deg(fg)<\deg(f)+\deg(g)$
August 1st, 2022
examples-counterexamples
abstract-algebra
polynomials
A set that is a countable intersection of open and dense sets but not open.
December 24th, 2020
examples-counterexamples
analysis
baire-category
Examples of types of mathematical models
August 1st, 2022
mathematical-modeling
examples-counterexamples
Example of a strictly convex function unbounded in $\mathbb{R}$
June 13th, 2020
examples-counterexamples
Example of two-dimensional non-abelian Lie algebra?
August 1st, 2022
lie-groups
lie-algebras
examples-counterexamples
What is a strictly convex function that is not strongly convex?
August 1st, 2022
convex-optimization
examples-counterexamples
convex-analysis
Complex Mean Value Theorem: Counterexamples
August 1st, 2022
examples-counterexamples
derivatives
complex-analysis
Shortest triangulation is in general not a Delaunay triangulation
August 1st, 2022
computational-geometry
examples-counterexamples
geometry
An epimorphism in $\text{Grp}$ without right inverse?
March 30th, 2020
category-theory
examples-counterexamples
group-theory
abstract-algebra
Why is a monoid with right identity and left inverse not necessarily a group?
August 1st, 2022
group-theory
semigroups
monoid
examples-counterexamples
Proving the derived set $E'$ is closed.
August 1st, 2022
general-topology
examples-counterexamples
Familiar spaces in which every one point set is $G_\delta$ but space is not first countable
August 1st, 2022
general-topology
examples-counterexamples
first-countable
Does there exist a Connected Locally Euclidean Space that is not second countable?
August 1st, 2022
general-topology
second-countable
connectedness
examples-counterexamples
←
1
2
3
4
5
6
7
8
9
…
24
25
→