# Questions tagged [terminology]

Questions of the kind "What's the name for a X that satisfies property Y?"

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### Terminology: are there any names for "quotients" of cellular towers in stable categories?

A cellular tower in SH or in a "more general stable homotopy category" is a chain of morphisms $\dots X^{(n)}\stackrel{g^n}{\to} X^{(n+1)}\to \dots$ along with some more data and conditions; ...
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### What's the terminology for a sequent-like variant of category?

Define a structure made of objects $A, B, C, \dots$ and morphisms $f, g, \dots$. Each morphism has a collection of domain objects and codomain objects. For simplicity we consider the domains and ...
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### English name and references for a combinatorial puzzle from Japan [closed]

I am looking for the name and references of the following puzzle. There are n intersecting circles in a row. At the center of the circle and at the intersection of the two circles, fill the numbers 1, ...
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### Name for a Hopf algebra whose only grouplike element is the identity?

For a $k$-Hopf algebra $H$ and element $h \in H$ is called grouplike is $\Delta(h) = h \otimes h$ and $\epsilon(h)=1_k$ ($\epsilon$ is the counit). The identity $1_H$ is clearly grouplike, but in ...
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### Who is Mrs. Gerber?

This question on a theorem in information theory called Mrs. Gerber's lemma piqued my curiosity. Who is this individual, and why the "mrs." ? A quick Google search was not informative, ...
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### Why are distributions "tempered"?

Google N-Gram shows that both "tempered distribution" and "temperate distribution" are used in English, but the first version significantly prevails, and usage of the second term ...
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### Name for a "non-injective" functor [duplicate]

Let $\mathcal{C}$ and $\mathcal{D}$ be two categories. Let $F:\mathcal{C} \to \mathcal{D}$ be a functor such that, for two non-isomorphic objects $x,y \in \mathcal{C}$ we have $$F(x) \simeq F(y).$$ ...
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### Word for two morphisms that are equivalent up to right-composition with isomorphism

Let $f:A\to C$, $g:B\to C$ be morphisms in some category. I call $f,g$ "equivalent" iff there exists an isomorphism $h$ such that $f\circ h=g$ (and consequently $g\circ h^{-1}=f$). Question:...
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### Question about terminology for a class of "self-modular" mappings between rings

(In the scenario I have in mind, rings need not be unital.) The following notion has come up in some joint work that is being written up. Let $R$ and $S$ be rings, and let $D$ be a subring of $R$. Is ...
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### Name for a type of assignment task

given a bipartite graph $G(U,V,E\subseteq U\times V)$ with strictly positive edge-weights; is there an established name for the the task of calculating the lightest spanning subgraph and what is the ...
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### Maximum size of vertex set with no induced connected component on more than k vertices

An independent set of a graph is a collection of vertices such that the induced subgraph consists of disconnected vertices. The maximum possible cardinality of an independent set is then called the ...
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### Pronunciation: the Erdős–Rado partition notation

The Erdős–Rado notation $a \rightarrow (b)^c_d$ is common in partition calculus / combinatorial set theory, as well as its negation $a \not\rightarrow (b)^c_d$. In that field, is there a standard way ...
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### What is the correct name of points with this property?

Let $(X, d)$ be a metric space and $x \in X$. Suppose for all $x_1, x_2 \in X$ the following inequality holds: $$d(x_1, x_2) \le \max \bigl\{ d(x, x_1), d(x, x_2) \bigr\}.$$ For example, singleton ...
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### Thirteen-point conic and four-point line, are they new?

We know that Five points determine a conic and Two Points Determine a Line. Here I found a simple construct of a conic through $7$ points (in PS I note that how the conic through thirteen points) and ...
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We introduce a new symbol $\lambda$ to denote class-abstractions, and we add the following rule: if $\phi$ is a formula that use $\mu"$, and in which the symbol $\sf y$ doesn't occur; then: $\lambda ... 1answer 138 views ### Do grammars with these properties have a name? I'm interested in context-free grammars on a finite set of symbols where all the production rules replace a symbol by a string of length two. There is also one constraint: in the reductive direction ... 1answer 218 views ### Are knot invariants topological invariants? [closed] I am a bit confused about terminology considering topology and knot theory. A topological invariant is considered to be a topological property that does not change under a homeomorphism of the space. ... 0answers 84 views ### Permutation group with a nice lattice of block systems Let$X$be a finite set and$G$be a transitive subgroup of the symmetric group on$X.$Recall that a (complete) block system for this action is a partition of$X = B_1 \cup \cdots \cup B_k$into ... 1answer 126 views ### Reference request: Spectrum of intersection matrices Let$P(A)$be the set of all non-empty proper subsets of a finite set$A$. Let$M$be a matrix indexed by the set in$P(A)$whose$ij$the entry is$1$if the associated sets are disjoint and$0$... 2answers 4k views ### Who started the "-oid" suffix fashion in math? There are lots of structures which have name suffixed by "oid". Off the top of my head, matroid, greedoid, perfectoid, causaloid... Who started this? AFAIK, "matroid", by Whitney, ... 1answer 223 views ### Given a unitary commutative ring$R$, what are the rings$R\langle x,y\rangle/(x^2-A,y^2-B,yx-a-bx-cy-dxy)\$ called
We are studying the rings $$R \langle x, \, y \rangle\,\big/\left(x^2-A, \, y^2-B, \, yx-a-bx-cy-dxy \right)$$ Do you know if they have a name?