The names tag has no wiki summary.

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### Why are they called 'pernicious' numbers?

The definition of a pernicious number:
In number theory, a pernicious number is a positive integer where the Hamming weight (or digit sum) of its binary representation is prime.
The meaning of ...

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### Name of a difference of continuants

I am getting ready to publish the manuscript
http://arxiv.org/pdf/1408.4631v2.pdf
and I am trying to do due diligence on a quantity I study before it gets published. (This is cross-posted from ...

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### The ten martini problem - reason for name

Why is the problem called the ten martini problem? Sounds like an interesting name for people who drink.

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### Morphisms every pushout of which is a weak equivalence

Let $M$ be a category equipped with a class of weak equivalences $W$. Is there a name for a morphism $f$ such that every pushout of $f$ (including, of course, $f$ itself) is a weak equivalence?
For ...

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### Naming ambiguity in constructive pointwise natural transformations and whiskering

In the HoTT Book, the choice is made to talk about whiskering, rather than horizontal composition, because horizontal composition is ambiguous and only defined up to paths. Naturally, there is left ...

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### How is Munkres pronounced? [closed]

How is the algebraic topologist James R. Munkres' last name "Munkres" pronounced? Is it "Munkrees" or "Munkers" or something else entirely? There is some disagreement among my acquaintances.
...

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### “Bell” or “Jabotinsky”-matrix - What's the canonical name (if any)?

I'm just reading J. Cigler's script for his talks "Konkrete Analysis" where I find the term "Jabotinsky-matrix" for that matrix, which I've (informally) been taught to call "Bell-matrix" (see at least ...

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### Generalising right-angled Artin groups

An Artin group $G$ is determined by its Coxeter matrix $M$. This is a symmetric $n \times n$ matrix with entries from $\lbrace 2, 3, \ldots, \infty \rbrace$ that determine the relations between the ...

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### Pronunciation: Vaughan Jones [closed]

Is it like "Vonn" as given here: http://www.merriam-webster.com/dictionary/vaughan

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### What is the quantity 2(handles)+crosscaps called?

It is well-known that up to homeomorphism, the complete set of orientable surfaces is $\lbrace S_g : g=0,1,\dots \rbrace$, where $S_g$ is the sphere with $g$ handles. The complete set of ...

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### fgf = f, gfg = g, fg not necessarily identity, what was that called?

A very simple question, I just totally forgot how it was called, and google is not helping.
There's a pair of functions $f:X\to Y$, $g:Y\to X$.
$fgf = f$, $gfg = g$, but $fg$ and $gf$ don't need to ...

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### Why are they called Spherical Varieties?

My understanding is if you have a homogeneous space $X = G/H$ for a reductive group $G$ and $X$ is normal and has an open $B$-orbit, for a Borel subgroup $B$ then you call $X$ spherical.
Someone ...

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### Names of finite groups

Question: If you have a finite group, how do you name it?
If, for whatever reason, you have to list all subgroups of $GL_2({\mathbb F}_5)$ up to isomorphism in a paper, you are likely to write ...

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### What do named “tricks” share?

There are a number of theorems or lemmas or mathematical ideas that come to be known as eponymous
tricks, a term which in this context is in no sense derogatory.
Here is a list of 10 such tricks (the ...

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### What's coherent about coherent sheaves?

In a recent answer to a recent question, BCnrd wrote
[...] beyond the coherent case one cannot expect information about a fiber (e.g., vanishing, 6 generators, etc.) to "propogate" to information ...

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### Name/references for analogue of ring with 2-cocycle condition instead of distributivity

I'm looking for a name for, and any past study on, the following kind of algebraic structure:
A set S equipped with an additive operation making it an abelian group, and a multiplication $*:S \times ...

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### Is this a pre-ordered commutative semigroup?

Motivation
I'm studying an approach to axiomatic thermodynamics based on the notion of commutative semigroup $(S,+)$ with a preorder relation $\to$ on $S$. In other words, $S$ is non-empty set, the ...

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### Knot database including text names

Knots such as the 3_1 knot and the 4_1 knot are often referred to as the trefoil and figure-eight knots respectively. There are more obscure names for some of the later ones in the knot tables, for ...

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### Binary matrices with constant row and column sums

My question is about $m \times n$ binary matrices (aka $\{0,1\}$-matrices), whose rows all sum to the same value, and whose columns all sum to the same value (but these two values may be different).
...

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### Have this subclass of split graphs been studied before?

I am interested in the properties of the following subclass of split graphs:
The class consists of all split graphs $G=(C\cup I)$ where $C$ is a clique and $I$ an independent set, and every pair of ...

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### Ethio Integers?

For introduction, Ethiointegers are integers which get reversed when multiplied by another number.
For instance,
2178 * 4 = 8712
1089 * 9 = 9801
I couldn't find such numbers, even by another name ...

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### What role does the “dual Coxeter number” play in Lie theory (and should it be called the “Kac number”)?

While trying to get some perspective on the extensive literature about highest weight modules for affine Lie algebras relative to "level" (work by Feigin, E. Frenkel, Gaitsgory, Kac, ....), I run into ...

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### Why “syntomic” if “flat, locally of finite presentation, and local complete intersection” is already available?

Dear everyone,
(i) Who is the father of the adjective “syntomic” in algebraic geometry?
(ii) And why did he choose to introduce a new term for what we already know from EGA IV.19.3.6 and SGA ...

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### What are examples of mathematical concepts named after the wrong people? (Stigler's law) [closed]

It's a common observation in Lie theory that Cartan matrices and the Killing form are named after the wrong people; they were discovered by Killing and Cartan, respectively. I remember learning about ...

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### Is there a mathematical object called “ivy”?

As the title says, is there a mathematical object referred to as "ivy" or "ivy type" or similar?
I have a type of graph where this name fits perfectly, but I don't want it to clash with something ...

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### Name for an inequality of isoperimetric type

I want to know if the following fact has a standard name and/or reference
Let $X$ be a subset of $\mathbb R^2$ and $B$ be a disc of the same area as $X$.
Set $X_\epsilon$ to be the ...

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### expected values over binomial distributions

In some works of economics/risk analysis etc., I have seen situations where people take the expected value of a function (such as a utility function/cost function) over a binomial distribution:
...

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### How do you pronounce “Hartshorne”? [closed]

What is the "correct" pronunciation of Robin Hartshorne's last name? Mostly I hear it pronounced "Har-shorn" although I've also heard "Harts-orn" and maybe a few other variations.

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### What does «generic» mean in algebraic geometry?

As a beginner, when I read some books in algebraic geometry such as the book complex projective variety by Mumford,I found a lot of "generic" object.
Could any one tell me how to understand "generic"?
...

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### Metric on one-point compactification

Is there a standard construction of a metric on one-point compactification of a proper metric space?
Comments:
A metric space is proper if all bounded closed sets are compact.
Standard means found ...

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### What's the origin of the naming convention for the standard basis of sl_2?

$\mathfrak{sl}_2(\mathbb{C})$ is usually given a basis $H, X, Y$ satisfying $[H, X] = 2X, [H, Y] = -2Y, [X, Y] = H$. What is the origin of the use of the letter $H$? (It certainly doesn't stand for ...

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### Algebra / unital associative algebra: better terminology?

In Bourbaki an algebra over a commutative ring $k$ is defined to be a $k$-module $A$ together with a $k$-bilinear map $A \times A \rightarrow A$. We then have the obvious notion of morphisms of ...

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### Riemann hypothesis generalization names: extended versus generalized?

This is a "names" question. There are two standard directions of generalization of the Riemann hypothesis: one to L-functions (which is used quite a bit in analytic number theory, and for extending ...

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### Cayley-Dickson form of a Quaternion

It is known that using the Cayley-Dickson construction a quaternion $q$ can be written in a symplectic form as $q=x+\mathbf{i}y$ with $x,y \in \mathbb{C}$.
I read in a couple of references that $x$ ...

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### Translation of “le nilradicalisé de g”

I apologize for asking something that might well be found in a mathematical dictionary, but the similarity of the French word to an English one is frustrating my attempts to Google the answer (and the ...

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### Name of upper triangular/lower triangular Lie Algebra decomposition

What is the name of the Lie algebra decomposition where the positive root vectors are upper triangular and the negative root vectors are lower triangular?

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### What is 'formal' ?

The key step in Kontsevich's proof of deformation quantization of Poisson manifolds is the so-called formality theorem where 'a formal complex' means that it admits a certain condition. I wonder why ...

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### Terminology: Name for a homomorphism from the free object?

Is there a standard name for taking a homomorphism from the free object over an algebraic structure? Roughly speaking, this should amount to evaluation of any element of the free object under the ...

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### Terminology: Is there a name for a category with biproducts?

Many people are familiar with the notion of an additive category. This is a category with the following properties:
(1) It contains a zero object (an object which is both initial and terminal).
...

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### What's the name of graphs with each vertex contained in a cycle?

A tree is a graph with no vertex contained in a cycle.
A non-tree is a graph with some vertex contained in a cyle.
What's the name of graphs with each
vertex contained in a cycle?

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### What do you call the product of a circle and an annulus?

What would you call the product of an annulus and $S^1$ (a 'thickened' torus like 3-manifold)?
More generally, is there an archive or list online of names assigned to various (non-standard) manifolds ...

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### Name for probabilistic version of Pascal's identity and differentiation formula for binomial distribution

I'm trying to find a standard name or standard reference for two simple-to-prove relations involving binomial distributions.
Define:
$b(n,r,p) := \binom{n}{r}p^r(1 - p)^{n-r}$
i.e., it is the ...

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### The eliminant of a system of differential equations

I am reading an old paper dealing with linear differential operators. At one point it refers to something it calls the "eliminant" of a set of linear differential operators. It seems that this was a ...

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### Standard name for basis-independent submatrices?

Given a linear map $T:H\to H$ on an inner-product space $H$ and a subspace $K\subseteq H$, define the map $T_K = \pi_K T \pi_K^* :K \to K$, where $\pi_K:H\to K$ is the orthogonal projection.
As an ...

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### What do you call this ring?

I want a ring $R$ of "numbers" such that:
For any sequence of congruences $x\equiv a_1 \pmod{n_1}, x\equiv a_2 \pmod{n_2},\dots$ with $a_i\in \mathbb{Z}$ and $n_i\in \mathbb{N}$ such than any finite ...

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### The proper name for a kind of ordered space

I'm trying to find the correct term for a specific kind of totally ordered space:
Let $S$ be a totally ordered space with asymmetric relation <.
Property: For any two $s_{1}$ and $s_{2}$ in $S$ ...

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### What's the standard name for sets of a given size with maximal probability (or a given probability and minimal size)?

The definition I'm going to give isn't quite the concept I really want, but it's a good approximation. I don't want to make the definition too technical and specific because if there's a standard name ...

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### A problem/conjecture related to 4-manifolds that deserves a name. What name does it deserve?

There's an old problem in 4-manifold theory that, as far as I know, doesn't have a name associated with it and really deserves a name.
Let $M$ be a smooth 4-manifold with boundary. Let $S$ be a ...

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### Is there a specific name for matrices with nonsingular principal submatrices?

Is there a specific name for matrices with nonsingular principal submatrices?