User tacos_tacos_tacos - Mathematics Stack Exchange

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1

8

votes

3

answers

202

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What does an outer automorphism look like?

may 18 at 14:13 azimut 5,498

3

votes

1

answer

51

views

Using the 6 sets of sets of 5 disjoint 2-cycles and the 3 sets of 5 pairwise disjoint triangles to exhibit an outer automorphism of $S_6$.

abstract-algebra combinatorics group-theory finite-groups symmetric-groups

may 18 at 11:22 azimut 5,498

4

votes

0

answers

26

views

Isomorphism between $E_8$ lattice and lattice defined by Extended Hamming Code

linear-algebra abstract-algebra combinatorics coding-theory

may 1 at 6:05 tacos_tacos_tacos 719

3

votes

1

answer

42

views

How many unique Hamming (7,4,3) Codes are there?

abstract-algebra combinatorics coding-theory

apr 27 at 10:29 Jyrki Lahtonen 30.9k

1

vote

2

answers

89

views

Classifying local behavior of fixed points using eigenvalues from linear stability analysis of 3D system

differential-equations dynamical-systems nonlinear-optimization

apr 23 at 20:34 nonlinearism 340

0

votes

1

answer

33

views

Generating vectors of the face-centered cubic lattice

geometry number-theory quadratic-forms integer-lattices

apr 22 at 4:32 Will Jagy 21.6k

2

votes

1

answer

45

views

Linear stability analysis on a constrained three-dimensional system of ODE

differential-equations dynamical-systems nonlinear-optimization

apr 20 at 5:16 Glen O 3,197

1

2

votes

0

answers

45

views

What kinds of sets are reasonable to place on the continuum?

real-analysis soft-question mathematical-modeling economics

apr 15 at 8:15 tacos_tacos_tacos 719

0

votes

3

answers

90

views

How to write “the parameter maximizing the maximum of the maximum value of two functions continuous in the domain of maximization”

algebra-precalculus multivariable-calculus optimization game-theory

apr 7 at 1:31 tacos_tacos_tacos 719

3

11

votes

2

answers

232

views

Algebraic interpretation of Lyapunov functions

abstract-algebra differential-equations

apr 1 at 20:05 Ilya 14.2k

0

votes

1

answer

56

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Closed orbits of SIR model variants

differential-equations stable-homotopy-theory

mar 30 at 23:02 Artem 2,548

1

vote

1

answer

74

views

Why can't gradient systems have closed orbits?

differential-equations multivariable-calculus dynamical-systems

mar 28 at 2:28 Brian Rushton 1,351

1

vote

1

answer

41

views

Half-stable vs saddle node

differential-equations terminology dynamical-systems

mar 22 at 5:07 Amzoti 14.1k

0

votes

1

answer

114

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Index of a sublattice in a lattice and a homomorphism between them

abstract-algebra group-theory integer-lattices

feb 28 at 21:16 YACP 9,190

2

7

votes

5

answers

199

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Simplest error detecting/correcting codes for math newbies

education coding-theory

feb 27 at 19:22 azimut 5,498

1

vote

0

answers

36

views

Half-stable fixed point on a circle

differential-equations bifurcation

jan 29 at 5:04 tacos_tacos_tacos 719

1

vote

1

answer

158

views

Mean preserving spread vs higher variance

probability stochastic-processes economics

jan 27 at 2:35 joriki 92.7k

2

4

votes

3

answers

112

views

Special properties of $\mathbb{R}^3$

general-topology euclidean-geometry

jan 20 at 8:00 Community♦ 1

2

votes

1

answer

68

views

Motivation for the term “transitive” group action

group-theory terminology group-actions

dec 11 at 7:35 Marc van Leeuwen 23.9k

3

votes

1

answer

87

views

Classifying all ideals of a lattice $\mathbb{Z}[\sqrt{-d}]$

abstract-algebra ring-theory ideals factoring integer-lattices

dec 5 at 15:31 Thom Tyrrell 415

3

5

votes

1

answer

145

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Showing that infinite product $\prod{(1+\frac{i}{k})}$ diverges

homework complex-analysis elementary-number-theory infinite-product

dec 5 at 5:52 WimC 8,618

0

votes

2

answers

63

views

Finding a basis for a complex lattice given a nondivisible vector in the lattice

linear-algebra abstract-algebra complex-numbers integer-lattices

nov 29 at 13:51 DonAntonio 47k

0

votes

0

answers

99

views

A homeomorphism from a semidisk to the unit disk

general-topology complex-analysis conformal-geometry

nov 25 at 5:26 tacos_tacos_tacos 719

0

votes

1

answer

41

views

Invariant factors of a Hadamard matrix divide the dimensionality of the matrix

linear-algebra abstract-algebra

nov 20 at 15:55 YACP 9,190

1

vote

1

answer

41

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Using Smith Normal Form to prove that even for a singular square matrix with entries in field $F$, $\exists U$ nonsingular where $(UA)^2 = UA$

linear-algebra abstract-algebra field-theory

nov 20 at 13:38 Martin Argerami 16.9k

1

vote

0

answers

65

views

Finding a conformal map between an irregular region between two disks and an annulus

complex-analysis

nov 16 at 3:13 tacos_tacos_tacos 719

1

vote

1

answer

75

views

A proof that the hexagonal lattice describes the optimal sphere packing in two dimensions

abstract-algebra geometry packing-problem

nov 15 at 4:14 Gerry Myerson 85.9k

4

15

votes

3

answers

346

views

How “abelian” can a non-abelian group be?

group-theory finite-groups abelian-groups

nov 13 at 16:24 Martino 254

1

vote

1

answer

310

views

Obtaining a generator polynomial from a parity check matrix for a binary cyclic code

abstract-algebra generating-functions coding-theory parity

nov 12 at 12:33 Jyrki Lahtonen 30.9k

1

vote

2

answers

34

views

How can I demonstrate the image of a contour in $\mathbb{C}$?

complex-analysis

nov 9 at 11:30 Per Manne 4,429

tacos_tacos_tacos

40 Questions