Questions tagged [symmetry]
Questions about symmetry, in group theory, geometry or elsewhere in mathematics. See https://en.wikipedia.org/wiki/Symmetry
1,634 questions
0 votes
1 answer
17 views
Showing positive definite quadratic forms give the "most symmetrical" metrics over $\mathbb{R}^n$
I was unsatisfied with the many proofs of the Pythagorean theorem in which it's not clearly apparent which axioms are specifically needed, or because said axioms seem too geometrically motivated in ...
0 votes
0 answers
37 views
If a representative part of a fractal-defined function lies entirely below the $y=x$ line, is this sufficient to guarantee no periodic points?
Consider a Cobweb diagram on the following function in the interval $(\frac12,1]$: The function is clearly arranged as a fractal, in fact its most obvious symmetry is $x\cong \dfrac{x+2}4$ By this ...
-1 votes
1 answer
42 views
Guessing the Symmetry figure
I took the image from the IGCSE maths problem, and the answer key says it has 3 symmetrical lines like this: How come? I think the answer key is incorrect? I even tried to print out it on the paper ...
0 votes
0 answers
26 views
Graph of Optimization Problem Transformations
In this lecture, Professor Stephen Boyd begins to draw a commutativity diagram to raise the question of whether transforming a program with strong duality into an equivalent problem and computing its ...
3 votes
3 answers
253 views
What exactly is a infinitesimal generator?
I am reading a book on symmetry methods for differential equations and trying to understand what exactly the infinitesimal generator is? (And what it describes geometrically, if it describes ...
7 votes
0 answers
148 views
Why do we care about invariant solutions of differential equations (under a one parameter Lie group)?
I am reading about symmetry methods on differential equations. It starts by considering invariant points, then orbits of points and invariant curves. It ends in a method to determine all (w.r.t Lie ...
3 votes
1 answer
211 views
Smallest overlapping circles containing unit circles in each section - Fifth arrangement
This question is related to my previous posts about overlapping circles, like this one. Another way of overlapping 3 circles looks like this: Once again, my question is, "How can these 3 circles ...
1 vote
1 answer
44 views
symmetry of a polytope after mapping one facet
When doing homework on algebra, on the symmetries of regular polygons and regular polyhedra, I observed, that mapping vertices of a single edge in regular polygon to another or mapping vertices of a ...
3 votes
4 answers
543 views
Must an inscribed parallelogram's center match the shape's symmetry center?
I have been studying centrally symmetric shapes (i.e., shapes with a center point $O$ such that for every point $P$ on the shape, there exists a point $P'$ where $O$ is the midpoint of $PP'$). When ...
0 votes
1 answer
79 views
Topology of projection matrices and symmetry matrices
Let $K = \mathbb{R}$ or $\mathbb{C}$ and $n \in \mathbb{N}, n \geqslant 2$. I was thinking about the topology of two subsets of $\mathfrak{M}_n(K)$ we don't talk about very often in Matrix Topology ...
13 votes
1 answer
2k views
Is there such a mathematical notion as 'antideterminant'?
The determinant of a matrix is given by the Leibniz formula $$\det(A) = \sum_{\tau \in S_n} \text{sgn}(\tau) \prod_{i = 1}^n a_{i\tau(i)} = \sum_{\sigma \in S_n} \text{sgn}(\sigma) \prod_{i = 1}^n a_{\...
2 votes
1 answer
39 views
Reflexive and Antisymmetric relation question
I'm reading Invitation to Discrete Mathematics (2nd edition) by Matousek and Nesetril. Page 41, problem #2 asks: Prove that a relation $R$ on a set $X$ satisfies $R ◦ R^{-1} = ∆X$ if and only if $R$ ...
0 votes
1 answer
56 views
Symmetric convex set in $\mathbb{R}^2$ with symmetry group exactly $\mathbb{Z}_n$ (no reflections)
Let $n \in \mathbb{N}$. I am looking for an explicit example of an open, bounded, symmetric, convex subset $C \subset \mathbb{R}^2$ whose full Euclidean symmetry group (that is, the group of ...
2 votes
0 answers
54 views
Prove that a finite point set cannot have more than one center of symmetry [closed]
This problem is taken form the Hungarian Problem Book III for math olympiads and this is problem 1935.2. In the solution it essentially assumes the existence of two centers of symmetry O and O' and ...
8 votes
1 answer
123 views
Geometric representation of finite groups
Looking for confirmation that the following method constructs a geometric object whose symmetry is described by a finite group $G$. Let $G$ be a finite group which is a subgroup of the symmetric group ...