symmetry is used in its general meaning, from symmetric matrices to Git. As a result you should probably use at least one more tag to describe your case better.
Questions tagged [symmetry]
78 questions
44
votes
4 answers
Are merges in Git symmetric?
Lets say we have two branches (B and C) that have diverged from a common ancestor A. Will merging from B to C produce the same result as merging from C to B?
A
|
/ \
B C
To clarify- I'm assuming that any manual merge conflict resolutions…
Eyal
- 3,412
- 1
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- 60
43
votes
2 answers
Graphviz Dot, mix directed and undirected
For my application I need to represent simultaneously (on the same graph) two relations: one is simmetric, the other is not.
Targets:
Ideally the two relation should result in edges having different colors;
For the symmetric relation I would like…
Dacav
- 13,590
- 11
- 60
- 87
22
votes
2 answers
Making a Read instance in Haskell
I have a data type
data Time = Time {hour :: Int,
minute :: Int
}
for which i have defined the instance of Show as being
instance Show Time where
show (Time hour minute) = (if hour > 10
…
Magnap
- 275
- 1
- 2
- 8
16
votes
3 answers
Eliminating symmetry from graphs
I have an algorithmic problem in which I have derived a transfer matrix between a lot of states. The next step is to exponentiate it, but it is very large, so I need to do some reductions on it. Specifically it contains a lot of symmetry. Below are…
Thomas Ahle
- 30,774
- 21
- 92
- 114
15
votes
3 answers
Computer algebra for Clojure
Short version:
I am interested in some Clojure code which will allow me to specify the transformations of x (e.g. permutations, rotations) under which the value of a function f(x) is invariant, so that I can efficiently generate a sequence of x's…
Gabriel Mitchell
- 979
- 5
- 17
13
votes
2 answers
Unicode characters having asymmetric upper/lower case. Why?
Why do the following three characters have not symmetric toLower, toUpper results
/**
* Written in the Scala programming language, typed into the Scala REPL.
* Results commented accordingly.
*/
/* Unicode Character 'LATIN CAPITAL LETTER SHARP…
Tim Friske
- 2,012
- 1
- 18
- 28
13
votes
1 answer
Python commutative operator override
Hi I was wondering if there is a way to do a symmetric operator override in Python. For example, let's say I have a class:
class A:
def __init__(self, value):
self.value = value
def __add__(self, other):
if isinstance(other,…
Bob Sacamano
- 699
- 15
- 39
9
votes
2 answers
N-Queens Symmetry Breaking Google OR Tools
One of the samples for the Google or-tools is a solver for the n-queens problem. At the bottom it says that the implementation can be improved by adding symmetry breaking constraints to the constraint solver.
Looking around the internet, I found…
Nick Larsen
- 18,631
- 6
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- 96
7
votes
2 answers
3D symmetry search algorithm
This may be more appropriate for math overflow, but nevertheless:
Given a 3D structure (for example, a molecule), what is a good approach/algorithm to find symmetry (rotational/reflection/inversion/etc.)?
I came up with brute force naïve algorithm,…
Anycorn
- 50,217
- 42
- 167
- 261
6
votes
2 answers
Permutation group implementation in Java
In my experience in programming, I often face with different tasks related to permutation group: enumerate all possible products of given permutations or just count them, test whether one permutation can be represented as a combination of given…
Stanislav Poslavsky
- 2,398
- 2
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- 36
6
votes
1 answer
Detection of symmetries in Python
I want to detect symmetries (rotation, translation, etc) of a simple figure or a shape in a image. That is, if I find one symmetry I want to replicate my original figure with it.
Are there any function or module?
I have thought in python-opencv, but…
kshipuden
- 93
- 1
- 4
6
votes
1 answer
An "asymmetric" pairwise distance matrix
Suppose there are three sequences to be compared: a, b, and c. Traditionally, the resulting 3-by-3 pairwise distance matrix is symmetric, indicating that the distance from a to b is equal to the distance from b to a.
I am wondering if TraMineR…
POTENZA
- 1,377
- 3
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- 20
5
votes
1 answer
How to represent Symmetry relationships in database modeling
If there is a symmetry relationship in a table, how to represent it in a elegant way?
For example, there is a table called Friend, in which should contain user ID of two users. If we use UID1 and UID2 in this table, when we want to find out if A_uid…
Ovilia
- 7,066
- 12
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- 70
5
votes
1 answer
How to exploit permutational symmetry in this loop?
I have a scalar function f(a,b,c,d) that has the following permutational symmetry
f(a,b,c,d) = f(c,d,a,b) = -f(b,a,d,c) = -f(d,c,b,a)
I'm using it to fully populate a 4D array. This code (using python/NumPy) below works:
A = np.zeros((N,N,N,N))
for…
jjgoings
- 225
- 2
- 6
5
votes
1 answer
Is ptr = free(ptr), NULL safe?
I'm writing code like this:
#include
int main(void)
{
void *kilobyte;
kilobyte = malloc(1024);
kilobyte = NULL, free(kilobyte);
return 0;
}
for symmetry, which is nice. But I've never seen anyone else using this idiom…
user2933244