Excavator - Badge - Mathematics Stack Exchange

Excavator

Edit first post that was inactive for 6 months.

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Convergence of interesting series $\sum_{p=0}^{\infty}\frac{1}{2^{p}}{k+p \choose k}$ [closed]

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kheory

233 bronze badges

A Conjecture in Low-Dimensional Topology.

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user1620463

32 bronze badges

Jensen inequality

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John

1134 bronze badges

How to prove the 5-lemma using subtraction of members?

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psl2Z

7,0569 silver badges24 bronze badges

f-related vector field

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Noel Lundström

5,2021 gold badge13 silver badges28 bronze badges

Proof of the theorem: Any $R$-module is contained in an $R$-injective module

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Muhammad Mursaleen

134 bronze badges

notation for real matrices

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Miquella

33 bronze badges

When $X^n-a$ is irreducible over F?

Awarded Nov 27 at 4:03

hdecristo

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3D plot of an orbit

Awarded Nov 27 at 4:03

Iq-n-dI

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How to show that a disjoint sum of metric spaces is metrizable?

Awarded Nov 27 at 4:03

Ulli

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Prove that $|x^p - y^p| \le p|x-y|(x^{p-1} + y^{p-1})$ provided that $1 \le p \lt \infty$ and $x, y \ge 0$

Awarded Nov 25 at 4:16

Klimace

134 bronze badges

Volume form for a product manifold.

Awarded Nov 24 at 5:38

Luke

1034 bronze badges

$\frac{G_1\times G_2}{N_1\times N_2}\cong \bigg(\frac{G_1}{N_1}\bigg)\times \bigg(\frac{G_2}{N_2}\bigg)$

Awarded Nov 24 at 5:38

anonymousclassjava

877 bronze badges

proper subgroups of finite p-groups are properly contained in the normalizer

Awarded Nov 23 at 6:16

user267839

10.1k4 gold badges23 silver badges106 bronze badges

For groups $A,B,C$, if $A\times B$ and $A\times C$ are isomorphic do we have $B$ isomorphic to $C$?

Awarded Nov 23 at 6:16

coconame

33 bronze badges

(post deleted or otherwise unavailable)

Awarded Nov 22 at 5:23

Dhairya Kumar

19017 bronze badges

Extension Theorem

Awarded Nov 21 at 6:02

zeta2

3802 silver badges7 bronze badges

Explanation of von Neumann minimax theorem

Awarded Nov 21 at 6:02

Matt Cushman

1851 silver badge11 bronze badges

Geometric interpretation of Hölder's inequality

Awarded Nov 19 at 6:56

Arthur

53 bronze badges

Is a hypersphere of non-integer dimension a fractal?

Awarded Nov 19 at 6:56

Ken Williams

2311 silver badge7 bronze badges

Why is continuity of partials necessary for Jacobian to be the derivative?

Awarded Nov 18 at 5:41

Trym Arve

555 bronze badges

Expected number of die rolls until obtaining three same consecutive numbers.

Awarded Nov 17 at 4:16

George Coote

2,2941 gold badge11 silver badges16 bronze badges

Root of unity filter

Awarded Nov 16 at 4:12

nullvector

33 bronze badges

Characteristic function of half normal distribution

Awarded Nov 15 at 4:32

AdamO

1076 bronze badges

Can someone please clarify combinations vs permutations?

Awarded Nov 13 at 4:48

abdul

32 bronze badges

What is a pullback of a metric, and how does it work?

Awarded Nov 12 at 4:08

Carl

1135 bronze badges

3D coordinates rotation -- new direction for Z axis

Awarded Nov 11 at 4:21

BitsAreNumbersToo

1356 bronze badges

This improper integral doesn't converge, does it?

Awarded Nov 10 at 4:01

DiamondNether90

538 bronze badges

Possible Error in Dedekind Construction of Stillwell's Book

Awarded Nov 10 at 4:01

SO Stinks

1036 bronze badges

Calculating perimeter of n-sided regular polygons using only height?

Awarded Nov 9 at 4:32

David Hammen

1882 silver badges9 bronze badges

Determining whether following sequences are Cauchy

Awarded Nov 8 at 4:41

absolutezero

4132 silver badges11 bronze badges

If you create a power tower of all the digits in a number, calculate that out, and repeat this process, will you always reach a single digit number?

Awarded Nov 6 at 5:13

Lucien Jaccon

8301 silver badge18 bronze badges

A System of Matrix Equations (2 Riccati, 1 Lyapunov)

Awarded Nov 5 at 4:25

lane-h-rogers

1231 silver badge6 bronze badges

what is the apparent size of a 1' object that is 600' away?

Awarded Nov 4 at 4:13

Daniel

1032 bronze badges

Counting Regular polygons in Complete Graphs

Awarded Nov 3 at 23:57

Sunny

3721 silver badge16 bronze badges

On Ji Chen's lemma

Awarded Nov 3 at 4:45

Chen Dan

5103 silver badges11 bronze badges

Suppose $a$ and $b$ are group elements, $a$ and $b$ commute, $|a|$ and $|b|$ are both finite. What are the possibilities for $|ab|$?

Awarded Nov 2 at 4:23

Fuat Ray

1,3644 silver badges16 bronze badges

How to reverse the $n$ choose $k$ formula?

Awarded Oct 31 at 4:10

Bennett D

32 bronze badges

Riemann-Stieltjes integral exercises

Awarded Oct 31 at 4:10

Lakshit Singh Bisht

236 bronze badges

For which number $a$ does the limit $f(x) = \lfloor x \rfloor$ exist?

Awarded Oct 30 at 4:17

TLo

1235 bronze badges

Spivak Chapter 7, Problem 19b: Continuity

Awarded Oct 26 at 6:53

user683

477 bronze badges

show this inequality if $\sum_{1\le i<j\le n}a_{i}a_{j}=\binom{n}{2}$

Awarded Oct 25 at 5:02

zhihan peng

37 bronze badges

Mental estimate for tangent of an angle (from $0$ to $90$ degrees)

Awarded Oct 24 at 5:00

Amadeus

456 bronze badges

How to extract the main diagonal of a matrix?

Awarded Oct 24 at 5:00

ambiguditi

1054 bronze badges

The fundamental group of preimage of covering map

Awarded Oct 24 at 5:00

Lipe Inostroza

73 bronze badges

Confusion about bounded nets and weak-* convergence vs. subsequences in reflexive spaces

Awarded Oct 24 at 5:00

Bill the Lizard

2163 silver badges12 bronze badges

Sum of terms whose differences are in Arithmetic progression.

Awarded Oct 23 at 4:06

Amelia Tearheart

1577 bronze badges

Every Finite Group is Isomorphic to a Subgroup of $A_n$ [closed]

Awarded Oct 23 at 4:06

Sebastian Nuñez

32 bronze badges

Irreducibility of $x^n + p^m \in \mathbb{Q}[x]$ where $m, n$ coprime.

Awarded Oct 22 at 5:21

Long-Ping Li

1,2452 silver badges15 bronze badges

Proving increasing sequence that converges is bounded

Awarded Oct 22 at 5:21

Roba

8375 silver badges17 bronze badges

Proving feasible direction in Linear Programming

Awarded Oct 21 at 4:22

Avni Badiwale

32 bronze badges

Exponential Growth Rates

Awarded Oct 21 at 4:22

artemetra

6743 silver badges18 bronze badges

I need to find all functions $f:\mathbb R \rightarrow \mathbb R$ which are continuous and satisfy $f(x+y)=f(x)+f(y)$

Awarded Oct 21 at 4:22

Daeree

399 bronze badges

Intuitive proof of multivariable changing of variables formula (Jacobian) without using mapping and/or measure theory?

Awarded Oct 20 at 4:42

Papa Smurf

2582 silver badges11 bronze badges

Computing all spanning trees of an undirected, regular grid (lattice)

Awarded Oct 19 at 5:03

Arthur Vause

5871 gold badge4 silver badges13 bronze badges

Radius vs Radius of curvature of an ellipse

Awarded Oct 17 at 4:31

Simon Branch

355 bronze badges

What is a term for two events where the absence of one assures the absence of the other?

Awarded Oct 16 at 13:37

Glory2Ukraine

2122 gold badges4 silver badges14 bronze badges

(post deleted or otherwise unavailable)

Awarded Oct 15 at 4:00

Wyatt Johnson

377 bronze badges

Is a sub-algebra of a semisimple algebra nescesarily isomorphic to a subset of its direct product decomposition via Wedderburn's classification?

Awarded Oct 15 at 4:00

eeerase

1816 bronze badges

exterior derivative vs connection: $d= \theta^i\wedge\nabla_{e_i}$

Awarded Oct 14 at 4:16

woodchuck

35 bronze badges

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