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5
votes
0answers
206 views

Primes for which 2 is a primitive root

I am writing a paper in which I keep referring to primes p for which 2 is a primitive root mod p and so I want to give a name for these primes. Is there a name for these primes in the literature ...
3
votes
2answers
114 views

Definition of the Moebius Ladder Graph

I found two different definitions of the Moebius Ladder Graph, whose essential difference is, whether the smallest one shall be $K_4$ or $K_{3,3}$. according to Wikipedia ...
3
votes
0answers
85 views

Correspondence between numerical semigroups and polynomials?

A numerical semigroup $A$ is defined as a subsemigroup of the semigroup $(\mathbb{N},+)$ of the positive integers such that the set $\mathbb{N}\setminus A$ is finite. Equivalently (for a subsemigroup) ...
2
votes
1answer
109 views

Terminology for the equation $a=a+b$ in commutative semigroups

Let $(S,+)$ be a commutative semigroup. For $a,b\in S$ consider the equation $a=a+b$. Does such a relation between the given $a$ and $b$ have a name? I am currently using such equations quite often ...
12
votes
1answer
674 views

Why the name “variety” and the notation “V” for zeroes of polynomials?

The following questions came to my mind while preparing the notes for the first class of (my first) course on algebraic geometry. Question 1: Is there any motivation for choosing the term "variety" ...
3
votes
1answer
196 views

Colorful model theory

There are a number of concepts in model theory - often situated around Hrushovski's amalgamation method (see for instance http://math.univ-lyon1.fr/~wagner/nijmegen.pdf) - which are colorfully named: ...
8
votes
1answer
487 views

Why are they called Specht Modules?

I know that the simple modules of $\mathbb{C}S_n$ are called $\it{Specht}$ $ \it{Modules}$, and they are named after the German Mathematician Wilhelm Specht because he studied them, but I think these ...
3
votes
1answer
339 views

What is the correct preposition? (And is there one?)

I just stumbled upon a linguistic problem I wasn't able to resolve via web search. Suppose we're given some geometric set $A$ and subset $B\subset A$. Isn't there a compact way of saying that there ...
2
votes
0answers
70 views

Terminology for real closure relative to a normal number field?

A real subfield $R\subseteq F$ of any number field has (finitely many) maximal real intermediate fields $R\subseteq R'\subseteq F$. Can I call such an $R'$ a real closure of $R$ relative to $F$? ...
2
votes
0answers
141 views

Why is a spectrum (in topology) called a spectrum? [duplicate]

The title says it all, I guess. Thank you for your answers.
8
votes
0answers
151 views

Earliest use of the term “linearly reductive”?

Recently a number of MO questions have referred to a "linearly reductive group", usually in a way that is out of focus. It's unclear to me why this terminology is so popular, since over a field of ...
27
votes
3answers
1k views

Why aren't fields called “bodies” instead?

The discrepancy regarding the names of commutative division algebras in German and English has always startled me. In English they are called fields, whereas their original German name is K├Ârper ...
7
votes
2answers
265 views

Why the term “monad” in homological algebra?

Which is the origin and the reason for the choice of the term "monad" in the sense of homological algebra? Does this concept have any relation whatsoever to the "monads" from category theory?
5
votes
1answer
360 views

Origin of the term “weight” in representation theory

In representation theory, there are the related concepts of weights and roots. Since both are kinds of generalised eigenvalues, and eigenvalues are roots of e.g. the characteristic polynomial, the ...
1
vote
0answers
141 views

Terminology question in model category theory

This is a terminology question. That will help me to write down my papers. In Marc Olschok's PhD available here (I cannot find it anymore on the Internet so it is in my webpage, the original URL is ...
4
votes
0answers
109 views

Nesting big-O with big-Omega $O(g(\Omega(h(n))))$: is it $O$ for all $\Omega$ or for one $\Omega$?

I want to express the following statement about a function $f(n)$: there exists $f_\Omega\in\Omega(h(n))$ such that $f\in O(g(f_\Omega(n))$. What's the correct notation for this? Is it $f\in ...
3
votes
3answers
184 views

Slice-category-like terminology question

Let $\mathcal C$ be a category, and consider a new category $\mathcal C'$ with $Obj(\mathcal C') := \{$pairs $(X \in Obj(\mathcal C), T \in End_{\mathcal C}(X)) \}$ $Hom_{\mathcal ...
4
votes
2answers
228 views

Is there a name for relations with this property, and the category of them?

The following math.stackexchange question asked whether there is a name for a certain sort of relation. I have become interested in the question, and no one suggested a name there, so I am asking ...
1
vote
1answer
89 views

Inverses of two-argument functions with respect to one argument

I asked a shorter version of this question at math.stackexchange.com four days ago but it hasn't gotten any answers or comments. Consider a function $f : A \times B \to C$ and two inverses, each with ...
3
votes
1answer
278 views

Is “ultracompact” taken?

Almost-huge cardinals are characterizable in terms of coherent towers of supercompactness measures, with a certain property of the direct limit model (see Kanamori's book). A useful large cardinal ...
0
votes
1answer
143 views

Terminology for a Partition of a Set which Includes Empty Sets

Mostly I see a partition of a set A defined as a collection of non-empty disjoint sets whose union is A. I see one reference that allows empty sets to be included in the partition: ("Potter, M. "Set ...
2
votes
0answers
164 views

“Extended” Weil Cohomology Theories

According to Wikipedia, a Weil cohomology theory is a functor from the category of smooth projective varieties over a field $k$, to graded algebras over a field $K$ of characteristic zero, together ...
1
vote
0answers
154 views

What is this structure called?

(I'm not entirely sure what to tag this; feel free to retag.) While thinking about automata (specifics below), I ran into the following phenomenon: A cofunction system is a pair of sets $X, A$, ...
3
votes
2answers
316 views

Terminology for blowups in algebraic geometry

This is a partial duplicate of this Stack Exchange question which unfortunately got no answer. All schemes are Noetherian and of finite type, although they need not be normal. With $Z \subset X$ a ...
6
votes
0answers
86 views

How to call a point in a space having the property that there is essentially one $\omega$-sequence converging to it?

Consider the point $x=\langle \omega_1,\omega\rangle$ in the Tychonov plank $(\omega_1 + 1)\times(\omega + 1)$. Then there is essentially only one sequence (of length $\omega$) converging to it, ...
2
votes
0answers
105 views

A generalization of quasi-identities

In universal algebra, a variety is axiomatized by identities $t \approx s$ between terms $t$ and $s$. More general are quasi-varieties that are axiomatized by quasi-identities of the form $$u_1 ...
5
votes
1answer
322 views

Where does the name “Reynolds operator” come from?

I always found it strange that, in the context of invariant and representation theory, averaging over the group is called the "Reynolds operator". As far as I know the work of Reynolds was in fluid ...
3
votes
1answer
153 views

Pairs of paths with the same source and target

Commutative diagrams usually express path equivalences in a category and thus involve pairs of paths in a category with the same source and target. General diagrams - in categories resp. category ...
0
votes
1answer
54 views

Name for a Specific Type of Non-Symmetric Bilinear Form

Let $V$ be a finite dimensional vector space, with some choice of basis $\{e_i\}_{i \in I}$. With respect to an idempotent bijection $B:I \to I$, define a bilinear form by $$ g = \sum_{i=1}^N ...
6
votes
1answer
224 views

Why stationary sets were named such?

My question is about terminology: Do you know why stationary sets were named such? Going over the following MO question about the intuition behind stationary sets, the only compelling argument I can ...
10
votes
2answers
500 views

What are Moschovakis cardinals?

The question is exactly that of the title: what are Moschovakis cardinals? Background. In a recent answer to the question, "Are there examples of statements that have been proven whose consistency ...
6
votes
1answer
192 views

Terminology question for poset maps

Is there a standard name for order-preserving maps $f\colon P\to Q$ of posets with the property that the image of a lower set is a lower set, or equivalently if $q\leq f(p)$ then there exists $p'\leq ...
3
votes
0answers
113 views

term for a rectangle with a bounded aspect ratio

I am writing a peper about dividing a shape into rectangles, where the main issue is to make sure that the rectangles have a limited aspect ratio. I am looking for a clear, unambiguous term for such ...
3
votes
0answers
153 views

choosing between the two ways to tropicalize

When tropicalizing a subtraction-free expression (see Do all subtraction-free identities tropicalize?), is it more common to replace addition by max or by min? Related issues: Is there a name for ...
2
votes
1answer
92 views

Hilbert's Finiteness Theorem for connected semisimple Lie groups in Weyl's “Classical Groups”

First of all, sorry for using this account. Somehow I can't login to my previous one anymore and am thus using the account associated to my MSE one. Also, I already asked the question on MSE, but ...
2
votes
2answers
55 views

Hilbert's Finiteness Theorem for connected semisimple Lie groups over $\mathbb{C}$ in Weyl's “Classical Groups” [duplicate]

In Nagata's "Lectures on the 14th problem of Hilbert" I found a reference to Weyl's "Classical Groups". Nagata writes that Weyl gives a positive answer to the original problem If ...
1
vote
0answers
69 views

Terminology question: maximal non-branching directed paths

Is there any special word for a maximal non-branching directed path in a network or diforest? To be 100% precise, by "maximal non-branching directed path" I mean a path $P=x_1,x_2,\ldots$ (maybe ...
14
votes
3answers
1k views

Who introduced the terms “equivalence relation” and “equivalence class”?

Consider that the question does not concern the origin of the ideas of equivalence relation and equivalence class. It exactly concerns the origin of the terms "equivalence relation" and "equivalence ...
4
votes
2answers
231 views

Name and notation for a binary operation

Is there a standard name or standard symbol for the binary operation that combines $x$ and $y$ to give $xy/(x+y)$, or equivalently $1/(1/x+1/y)$? (At least the expressions are equivalent if we ignore ...
3
votes
2answers
255 views

Term for “Directed acyclic graph with exactly one sink and one source”

There's a theorem/lemma that states that a finite directed acyclic graph (DAG) has at least one sink and at least one source. Is there a term for a (finite) DAG with exactly one sink and one source? ...
0
votes
0answers
101 views

Notation to distinguish simplicial sets and semisimplicial sets

Usually one writes $X_\bullet$ both for simplicial sets and for semisimplicial sets. But this is potentially confusing if I want to consider maps $X_\bullet\to Y_\bullet^\text{forget}$ in the ...
8
votes
1answer
269 views

Question about tetrahedron decomposition

Are there tetrahedra which can be subdivided into three parts similar to the original? I believe this would require splitting one face into three parts. I know some types of tetrahedron for which this ...
1
vote
2answers
118 views

Terminology: complex of sheaves with cohomology sheaves concentrated in degree zero

What is the proper terminology for a complex of sheaves $\mathcal F^\bullet$ whose homology sheaves $\mathcal H^i\mathcal F^\bullet$ vanish for $i\ne 0$?
2
votes
0answers
463 views

Is there a name for this graph?

I'm trying to find out whether the following graph has a name: Let $W$ be an $n$-dimensional vector space over $GF(q)$. The vertices of the graph are all the subspaces of $W$. Two subspaces $W_1$ and ...
9
votes
1answer
399 views

Does this property of a partially ordered set have a name?

What do you call a poset with this property? For any elements $a,b,c,d$ such that $\{a,b\}\le\{c,d\}$, there is an element x such that $\{a,b\}\le x\le\{c,d\}$. (Equivalently, for any finite sets ...
1
vote
0answers
59 views

Term for function with this property?

Is there a name for functions with the following property (a la transitive relations)? If $F(X \cup \{a\}) = y$ and $F(X \cup \{b\}) = y$ then $F(X \cup \{a,b\}) = y$
8
votes
2answers
301 views

central/critical/special values of L-functions terminology

I have a question about the terminology for special values of L-functions. Is the following a correct description of standard usage: Suppose L(s) is an L-function which satisfies a functional ...
4
votes
5answers
382 views

What is “Data” involved in a mathematical construction?

What exactly do mathematicians mean when they refer to "the data" involved in a construction? I've encountered this many times and I can usually figure out what's going on, but I am curious about the ...
0
votes
1answer
92 views

Is there a proper way to define a threshold vertex density for a random graph s.t. the graph is fully connected?

Imagine one generates some form of random graph (e.g. a random geometric graph) and via simulation, calculates the probability that there exists an edge-wise path between all vertices in the graph as ...
25
votes
9answers
3k views

Is there a “mathematical” definition of “simplify”?

Every mathematician knows what "simplify" means, at least intuitively. Otherwise, he or she wouldn't have made it through high school algebra, where one learns to "simplify" expressions like ...