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Alphabet & Symbols

Latin (upright & italic)

$\mathrm{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$

$A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z$

$\mathrm{a\,b\,c\,d\,e\,f\,g\,h\,i\,j\,k\,l\,m\,n\,o\,p\,q\,r\,s\,t\,u\,v\,w\,x\,y\,z}$

$a\,b\,c\,d\,e\,f\,g\,h\,i\,j\,k\,l\,m\,n\,o\,p\,q\,r\,s\,t\,u\,v\,w\,x\,y\,z$

$0\;1\;2\;3\;4\;5\;6\;7\;8\;9$

Greek (uppercase — only non-Latin forms have commands)

$\Gamma\;\Delta\;\Theta\;\Lambda\;\Xi\;\Pi\;\Sigma\;\Upsilon\;\Phi\;\Psi\;\Omega$

Greek (lowercase)

$\alpha\;\beta\;\gamma\;\delta\;\epsilon\;\zeta\;\eta\;\theta\;\iota\;\kappa\;\lambda\;\mu\;\nu\;\xi\;\pi\;\rho\;\sigma\;\tau\;\upsilon\;\phi\;\chi\;\psi\;\omega$

Greek (variant forms)

$\varepsilon\;\vartheta\;\varkappa\;\varpi\;\varrho\;\varsigma\;\varphi$

Blackboard bold, Calligraphic, Fraktur

$\mathbb{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$

$\mathcal{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$

$\mathfrak{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$

Operators & Relations

$+ \;-\; \times\; \div\; \pm\; \mp\; \cdot\; \circ\; \star\; \ast\; \bullet\; \oplus\; \otimes\; \odot$

$= \;\neq\; <\; >\; \leq\; \geq\; \ll\; \gg\; \approx\; \sim\; \simeq\; \cong\; \equiv\; \propto$

$\in\; \notin\; \ni\; \subset\; \supset\; \subseteq\; \supseteq\; \cap\; \cup\; \setminus\; \emptyset$

$\forall\; \exists\; \nexists\; \neg\; \land\; \lor\; \Rightarrow\; \Leftrightarrow\; \vdash\; \models\; \top\; \bot$

$\infty\; \partial\; \nabla\; \triangle\; \square\; \hbar\; \ell\; \wp\; \Re\; \Im\; \aleph$

Typography Matrix — Style Variants

Tests all four style combinations (upright, italic, bold upright, bold italic) for Latin and Greek. Each row should use the text font's own glyphs, not the math font's.

Uppercase Latin
Upright (mathrm)$\mathrm{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$
Italic (default)$A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z$
Bold upright (mathbf)$\mathbf{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$
Bold italic (boldsymbol)$\boldsymbol{A\,B\,C\,D\,E\,F\,G\,H\,I\,J\,K\,L\,M\,N\,O\,P\,Q\,R\,S\,T\,U\,V\,W\,X\,Y\,Z}$
Lowercase Latin
Upright (mathrm)$\mathrm{a\,b\,c\,d\,e\,f\,g\,h\,i\,j\,k\,l\,m\,n\,o\,p\,q\,r\,s\,t\,u\,v\,w\,x\,y\,z}$
Italic (default)$a\,b\,c\,d\,e\,f\,g\,h\,i\,j\,k\,l\,m\,n\,o\,p\,q\,r\,s\,t\,u\,v\,w\,x\,y\,z$
Bold upright (mathbf)$\mathbf{a\,b\,c\,d\,e\,f\,g\,h\,i\,j\,k\,l\,m\,n\,o\,p\,q\,r\,s\,t\,u\,v\,w\,x\,y\,z}$
Bold italic (boldsymbol)$\boldsymbol{a\,b\,c\,d\,e\,f\,g\,h\,i\,j\,k\,l\,m\,n\,o\,p\,q\,r\,s\,t\,u\,v\,w\,x\,y\,z}$
Uppercase Greek
Upright (default)$\Gamma\;\Delta\;\Theta\;\Lambda\;\Xi\;\Pi\;\Sigma\;\Upsilon\;\Phi\;\Psi\;\Omega$
Italic (varGamma etc.)$\varGamma\;\varDelta\;\varTheta\;\varLambda\;\varXi\;\varPi\;\varSigma\;\varUpsilon\;\varPhi\;\varPsi\;\varOmega$
Bold upright (boldsymbol)$\boldsymbol{\Gamma}\;\boldsymbol{\Delta}\;\boldsymbol{\Theta}\;\boldsymbol{\Lambda}\;\boldsymbol{\Xi}\;\boldsymbol{\Pi}\;\boldsymbol{\Sigma}\;\boldsymbol{\Upsilon}\;\boldsymbol{\Phi}\;\boldsymbol{\Psi}\;\boldsymbol{\Omega}$
Bold italic$\boldsymbol{\varGamma}\;\boldsymbol{\varDelta}\;\boldsymbol{\varTheta}\;\boldsymbol{\varLambda}\;\boldsymbol{\varXi}\;\boldsymbol{\varPi}\;\boldsymbol{\varSigma}\;\boldsymbol{\varUpsilon}\;\boldsymbol{\varPhi}\;\boldsymbol{\varPsi}\;\boldsymbol{\varOmega}$
Lowercase Greek
Upright (mathrm)$\mathrm{\alpha\;\beta\;\gamma\;\delta\;\epsilon\;\zeta\;\eta\;\theta\;\iota\;\kappa\;\lambda\;\mu\;\nu\;\xi\;\pi\;\rho\;\sigma\;\tau\;\upsilon\;\phi\;\chi\;\psi\;\omega}$
Italic (default)$\alpha\;\beta\;\gamma\;\delta\;\epsilon\;\zeta\;\eta\;\theta\;\iota\;\kappa\;\lambda\;\mu\;\nu\;\xi\;\pi\;\rho\;\sigma\;\tau\;\upsilon\;\phi\;\chi\;\psi\;\omega$
Bold upright$\boldsymbol{\mathrm{\alpha\;\beta\;\gamma\;\delta\;\epsilon\;\zeta\;\eta\;\theta\;\iota\;\kappa\;\lambda\;\mu\;\nu\;\xi\;\pi\;\rho\;\sigma\;\tau\;\upsilon\;\phi\;\chi\;\psi\;\omega}}$
Bold italic (boldsymbol)$\boldsymbol{\alpha\;\beta\;\gamma\;\delta\;\epsilon\;\zeta\;\eta\;\theta\;\iota\;\kappa\;\lambda\;\mu\;\nu\;\xi\;\pi\;\rho\;\sigma\;\tau\;\upsilon\;\phi\;\chi\;\psi\;\omega}$
Greek variant forms
Italic (default)$\varepsilon\;\vartheta\;\varkappa\;\varpi\;\varrho\;\varsigma\;\varphi$
Bold italic$\boldsymbol{\varepsilon}\;\boldsymbol{\vartheta}\;\boldsymbol{\varkappa}\;\boldsymbol{\varpi}\;\boldsymbol{\varrho}\;\boldsymbol{\varsigma}\;\boldsymbol{\varphi}$
Mixed Latin + Greek (height consistency check)
Regular$U \Sigma V^T \quad \alpha x + \beta y = \gamma z \quad \Gamma(n) = (n-1)!$
Bold$\mathbf{U} \boldsymbol{\Sigma} \mathbf{V}^T \quad \boldsymbol{\alpha} \mathbf{x} + \boldsymbol{\beta} \mathbf{y} = \boldsymbol{\gamma} \mathbf{z} \quad \boldsymbol{\Gamma}(\mathbf{n}) = (\mathbf{n}-1)!$
Mixed bold/regular caps$\mathbf{A}\Sigma\mathbf{B}\Gamma \quad \boldsymbol{\Sigma} = U \Lambda U^T \quad P(\mathbf{X}) = \boldsymbol{\Theta}\,\Phi(X) \quad \mathbf{M}\Delta\mathbf{N}\Omega$
Mixed (expressions)$\boldsymbol{\mu} = \frac{1}{n}\sum_{i=1}^n \mathbf{x}_i \quad \boldsymbol{\Sigma} = \mathbb{E}[(\mathbf{x}-\boldsymbol{\mu})(\mathbf{x}-\boldsymbol{\mu})^T] \quad \rho(\mathbf{A}) = \max|\lambda_i|$
Mixed (physics)$\boldsymbol{F} = m\mathbf{a} \quad \boldsymbol{\omega} \times \mathbf{r} = \mathbf{v} \quad \boldsymbol{\nabla} \cdot \mathbf{E} = \frac{\rho}{\varepsilon_0} \quad \Psi(\mathbf{r},t) = \phi(\mathbf{r})e^{-i\omega t}$
Greek/Latin scaling checks (large)

$b\beta p\beta a\beta f\beta$   $\mathrm{b\beta p\beta a\beta f\beta}$   $\mathbf{b}\boldsymbol{\beta}\mathbf{p}\boldsymbol{\beta}\mathbf{a}\boldsymbol{\beta}\mathbf{f}\boldsymbol{\beta}$

$\alpha\boldsymbol{\alpha}$   $\beta\boldsymbol{\beta}$   $\gamma\boldsymbol{\gamma}$   $\theta\boldsymbol{\theta}$   $\sigma\boldsymbol{\sigma}$   $\Sigma\boldsymbol{\Sigma}$   $\Gamma\boldsymbol{\Gamma}$   $\Omega\boldsymbol{\Omega}$

$A\Sigma B\Gamma C\Omega$   $\mathbf{A}\boldsymbol{\Sigma}\mathbf{B}\boldsymbol{\Gamma}\mathbf{C}\boldsymbol{\Omega}$   $x\alpha y\beta z\gamma$   $\mathbf{x}\boldsymbol{\alpha}\mathbf{y}\boldsymbol{\beta}\mathbf{z}\boldsymbol{\gamma}$

Integrals & Large Operators

Inline integrals (subscript/superscript positioning)

$\int_a^b f(x)\,dx$   $\int_0^1 g(t)\,dt$   $\int_\Omega \nabla u \cdot \nabla v\,dx$   $\int_{-\infty}^{\infty} e^{-x^2}\,dx$   $\oint_\gamma f(z)\,dz$

$\iint_\Omega f\,dA$   $\iiint_V \rho\,dV$   $\int_0^\pi \sin\theta\,d\theta$   $\int_a^b \int_c^d f(x,y)\,dy\,dx$

Inline integrals in prose

The fundamental theorem of calculus states that if $F$ is an antiderivative of $f$, then $\int_a^b f(x)\,dx = F(b) - F(a)$. For instance, $\int_0^1 x^2\,dx = \frac{1}{3}$ and $\int_0^\pi \sin\theta\,d\theta = 2$. The Gaussian integral $\int_{-\infty}^{\infty} e^{-x^2}\,dx = \sqrt{\pi}$ appears throughout probability and physics.

In complex analysis, the residue theorem gives $\oint_\gamma f(z)\,dz = 2\pi i \sum_k \operatorname{Res}(f, z_k)$, where the integral is taken over a closed contour $\gamma$. For multivariable calculus, the divergence theorem relates $\iiint_V \nabla \cdot \mathbf{F}\,dV = \iint_{\partial V} \mathbf{F}\cdot\mathbf{n}\,dS$. The energy of a signal $f$ is $E = \int_0^T |f(t)|^2\,dt$, and the Fourier transform is $\hat{f}(\xi) = \int_{-\infty}^{\infty} f(x)\,e^{-2\pi i x \xi}\,dx$.

Display integrals
$$\int_a^b f(x)\,dx = F(b) - F(a)$$
$$\int_0^\infty e^{-x^2}\,dx = \frac{\sqrt{\pi}}{2}$$
$$\oint_\gamma f(z)\,dz = 2\pi i \sum_k \operatorname{Res}(f, z_k)$$
$$\iint_\Omega \nabla u \cdot \nabla v\,dx = \int_\Omega f\,v\,dx \quad \forall v \in H_0^1(\Omega)$$
Inline large operators

$\sum_{i=1}^n a_i$   $\prod_{j=1}^m b_j$   $\coprod_{k \in K} G_k$   $\bigcup_{i=1}^n A_i$   $\bigcap_{i=1}^n A_i$

Display large operators
$$\sum_{i=1}^{n} a_i = a_1 + a_2 + \cdots + a_n$$
$$\prod_{i=1}^{n} \left(1 + \frac{x}{i}\right) \qquad \coprod_{\alpha \in A} G_\alpha$$
Integral sub/super alignment check (large, look for centering)

$\int_a^b$   $\int_0^1$   $\int_\Omega$   $\oint_\gamma$   $\iint_D$   $\iiint_V$

$\sum_{i=1}^n$   $\prod_{j=1}^m$   $\bigcup_{k}^{}$   $\bigcap_{k}^{}$

Text–Math Harmonization

Inline math in prose (cap height, x-height, weight)

The matrix $A$ has eigenvalues $\lambda_1, \ldots, \lambda_n$. Let $X$ be a topological space and $L$ a line bundle. The function $f(x) = e^{-x^2}$ is in $L^2(\mathbb{R})$. We define $T : V \to W$ where $V$ and $W$ are Banach spaces.

Capital letters: text vs math interleaved

A $A$ B $B$ C $C$ D $D$ E $E$ F $F$ G $G$ H $H$ I $I$ J $J$ K $K$ L $L$ M $M$ N $N$ O $O$ P $P$ Q $Q$ R $R$ S $S$ T $T$ U $U$ V $V$ W $W$ X $X$ Y $Y$ Z $Z$

Capital letters: text vs bold math interleaved

A $\mathbf{A}$ B $\mathbf{B}$ C $\mathbf{C}$ D $\mathbf{D}$ E $\mathbf{E}$ F $\mathbf{F}$ G $\mathbf{G}$ H $\mathbf{H}$ I $\mathbf{I}$ J $\mathbf{J}$ K $\mathbf{K}$ L $\mathbf{L}$ M $\mathbf{M}$

Lowercase: text vs math interleaved

a $a$ b $b$ c $c$ d $d$ e $e$ f $f$ g $g$ h $h$ i $i$ j $j$ k $k$ l $l$ m $m$ n $n$ o $o$ p $p$ q $q$ r $r$ s $s$ t $t$ u $u$ v $v$ w $w$ x $x$ y $y$ z $z$

Digits: text vs math interleaved

0 $0$ 1 $1$ 2 $2$ 3 $3$ 4 $4$ 5 $5$ 6 $6$ 7 $7$ 8 $8$ 9 $9$

Mixed text and math sizing

If $n \geq 3$ then the group $G$ acts on $X$ with $|G| = 12$. The constant $C > 0$ satisfies $C \leq M$ for all $M$ in the set $S$. Theorem 3.1 states that $\|Tx\| \leq K\|x\|$ for every $x \in H$.

Linear Algebra

Let $V$ be a finite-dimensional vector space over $\F$ with basis $\{e_1, \ldots, e_n\}$. A linear map $T : V \to W$ is represented by a matrix $\mathbf{A} \in \F^{m \times n}$ whose entries are $a_{ij} = \langle w_i^*, T(e_j) \rangle$.

$$\mathbf{A} = \begin{pmatrix} a_{11} & a_{12} & \cdots & a_{1n} \\ a_{21} & a_{22} & \cdots & a_{2n} \\ \vdots & \vdots & \ddots & \vdots \\ a_{m1} & a_{m2} & \cdots & a_{mn} \end{pmatrix}$$

The eigenvalue problem seeks $\lambda \in \C$ and $\mathbf{v} \neq \mathbf{0}$ such that $\mathbf{A}\mathbf{v} = \lambda\mathbf{v}$, equivalently $\det(\mathbf{A} - \lambda \mathbf{I}) = 0$. The characteristic polynomial is

$$p(\lambda) = \det(\mathbf{A} - \lambda \mathbf{I}) = \sum_{k=0}^{n} (-1)^k \, e_{n-k}(\mathbf{A})\, \lambda^k$$

where $e_k(\mathbf{A})$ is the $k$-th elementary symmetric polynomial of the eigenvalues. By the Cayley–Hamilton theorem, $p(\mathbf{A}) = \mathbf{0}$.

The singular value decomposition factors any $\mathbf{A} \in \R^{m \times n}$ as

$$\mathbf{A} = \mathbf{U} \boldsymbol{\Sigma} \mathbf{V}^\top, \qquad \boldsymbol{\Sigma} = \operatorname{diag}(\sigma_1, \ldots, \sigma_r, 0, \ldots, 0)$$

where $\mathbf{U} \in \R^{m \times m}$ and $\mathbf{V} \in \R^{n \times n}$ are orthogonal, $\sigma_1 \geq \cdots \geq \sigma_r > 0$, and $r = \rank(\mathbf{A})$. The Neumann series $(I - \lambda \mathbf{A})^{-1} = \sum_{k=0}^{\infty} \lambda^k \mathbf{A}^k$ converges when $|\lambda| \cdot \|\mathbf{A}\| < 1$.

Analysis & Partial Differential Equations

Let $\Omega \subset \R^n$ be a bounded domain with smooth boundary $\partial\Omega$. Consider the Dirichlet problem for the Laplacian:

$$\begin{cases} -\Delta u = f & \text{in } \Omega, \\ u = g & \text{on } \partial\Omega, \end{cases}$$

where $\Delta u = \sum_{i=1}^{n} \dfrac{\partial^2 u}{\partial x_i^2}$ is the Laplacian. A weak solution $u \in H^1(\Omega)$ satisfies

$$\int_\Omega \nabla u \cdot \nabla v \, dx = \int_\Omega f \, v \, dx \qquad \forall\, v \in H^1_0(\Omega).$$

By the Lax–Milgram theorem, existence and uniqueness follow from the coercivity $\|\nabla u\|_{L^2}^2 \geq C \|u\|_{H^1}^2$ (Poincaré inequality).

The heat equation $\partial_t u - \Delta u = 0$ on $\R^n \times (0,\infty)$ has fundamental solution

$$\Phi(x, t) = \frac{1}{(4\pi t)^{n/2}} \exp\!\left(-\frac{|x|^2}{4t}\right), \qquad t > 0.$$

The Fourier transform $\hat{f}(\xi) = \int_{\R^n} f(x)\, e^{-2\pi i \langle x, \xi\rangle}\, dx$ satisfies Parseval's identity $\|\hat{f}\|_{L^2} = \|f\|_{L^2}$ and the convolution theorem $\widehat{f * g} = \hat{f} \cdot \hat{g}$.

Topology & Geometry

Let $(X, \tau)$ be a topological space. A sequence of covers $\mathcal{U}_1 \succ \mathcal{U}_2 \succ \cdots$ refining each other gives rise to the Čech cohomology groups

$$\check{H}^q(X; \, \mathcal{F}) = \varinjlim_{\mathcal{U}} H^q(\mathcal{U}; \, \mathcal{F})$$

where $\mathcal{F}$ is a sheaf on $X$. For a compact oriented $n$-manifold $M$ without boundary, Poincaré duality gives an isomorphism

$$H^k(M; \, \Z) \cong H_{n-k}(M; \, \Z)$$

and the Euler characteristic satisfies $\chi(M) = \sum_{k=0}^{n} (-1)^k \, b_k$ where $b_k = \rank H_k(M; \, \Z)$ are the Betti numbers.

The Gauss–Bonnet theorem for a compact surface $\Sigma$ states

$$\int_\Sigma K \, dA + \int_{\partial\Sigma} \kappa_g \, ds = 2\pi \, \chi(\Sigma)$$

where $K$ is the Gaussian curvature and $\kappa_g$ is the geodesic curvature of the boundary. For a closed surface, this reduces to $\int_\Sigma K \, dA = 2\pi\,\chi(\Sigma)$.

The long exact sequence of a fibration $F \hookrightarrow E \twoheadrightarrow B$ is

$$\cdots \to \pi_{n+1}(B) \xrightarrow{\;\partial\;} \pi_n(F) \xrightarrow{\;i_*\;} \pi_n(E) \xrightarrow{\;p_*\;} \pi_n(B) \xrightarrow{\;\partial\;} \pi_{n-1}(F) \to \cdots$$

Combinatorics & Discrete Mathematics

The number of ways to partition a set of $n$ elements into $k$ non-empty subsets is the Stirling number of the second kind, given by

$$S(n, k) = \frac{1}{k!} \sum_{j=0}^{k} (-1)^{k-j} \binom{k}{j} j^n.$$

The exponential generating function is $\sum_{n \geq k} S(n,k)\, \frac{x^n}{n!} = \frac{(e^x - 1)^k}{k!}$.

The Catalan numbers $C_n = \frac{1}{n+1}\binom{2n}{n}$ count the number of Dyck paths from $(0,0)$ to $(2n,0)$. Their generating function satisfies

$$C(x) = \sum_{n=0}^{\infty} C_n x^n = \frac{1 - \sqrt{1 - 4x}}{2x} = \frac{2}{1 + \sqrt{1 - 4x}}.$$

By the matrix-tree theorem, the number of spanning trees of a graph $G$ on $n$ vertices equals any cofactor of the Laplacian $\mathbf{L} = \mathbf{D} - \mathbf{A}$:

$$\tau(G) = \frac{1}{n} \lambda_1 \lambda_2 \cdots \lambda_{n-1}$$

where $0 = \lambda_0 \leq \lambda_1 \leq \cdots \leq \lambda_{n-1}$ are the eigenvalues of $\mathbf{L}$. The chromatic polynomial $\chi_G(k)$ counts proper $k$-colorings and satisfies the deletion–contraction recurrence $\chi_G(k) = \chi_{G-e}(k) - \chi_{G/e}(k)$.

Probability & Statistics

Let $X_1, X_2, \ldots$ be i.i.d. random variables with $\E[X_i] = \mu$ and $\operatorname{Var}(X_i) = \sigma^2 < \infty$. The central limit theorem states

$$\frac{\bar{X}_n - \mu}{\sigma / \sqrt{n}} \xrightarrow{\;d\;} \mathcal{N}(0, 1) \qquad \text{as } n \to \infty$$

where $\bar{X}_n = \frac{1}{n}\sum_{i=1}^n X_i$. The density of $\mathcal{N}(\mu, \sigma^2)$ is

$$f(x) = \frac{1}{\sigma\sqrt{2\pi}} \exp\!\left(-\frac{(x - \mu)^2}{2\sigma^2}\right).$$

For a Markov chain with transition matrix $\mathbf{P} = (p_{ij})$, the stationary distribution $\boldsymbol{\pi}$ satisfies $\boldsymbol{\pi}^\top \mathbf{P} = \boldsymbol{\pi}^\top$ and $\sum_i \pi_i = 1$. The ergodic theorem gives

$$\P\!\left(\lim_{n \to \infty} \frac{1}{n} \sum_{k=0}^{n-1} \mathbf{1}_{X_k = j} = \pi_j\right) = 1.$$

Bayes' theorem: $\P(A \mid B) = \dfrac{\P(B \mid A)\,\P(A)}{\P(B)}$, or in density form, $f_{\Theta|X}(\theta \mid x) \propto f_{X|\Theta}(x \mid \theta) \, f_\Theta(\theta)$.

Abstract Algebra

Let $G$ be a finite group acting on a set $S$. By Burnside's lemma, the number of distinct orbits is

$$|S / G| = \frac{1}{|G|} \sum_{g \in G} |S^g|$$

where $S^g = \{s \in S : g \cdot s = s\}$ is the fixed-point set of $g$.

For a Galois extension $L/K$ with $\Gal(L/K) \cong G$, the fundamental theorem of Galois theory establishes a bijection

$$\{\text{intermediate fields } K \subseteq E \subseteq L\} \;\longleftrightarrow\; \{\text{subgroups } H \leq G\}$$

given by $E \mapsto \Gal(L/E)$ and $H \mapsto L^H$, where $[E : K] = [G : H]$.

In a principal ideal domain $R$, every finitely generated module $M$ decomposes as

$$M \cong R^r \oplus \bigoplus_{i=1}^{s} R/(p_i^{a_i})$$

where $r = \rank(M)$ and $p_1^{a_1}, \ldots, p_s^{a_s}$ are the elementary divisors. For $R = \Z$, this gives the classification of finitely generated abelian groups.

Physics

Maxwell's equations in differential form (Gaussian units):

$$\nabla \cdot \mathbf{E} = 4\pi\rho, \qquad \nabla \times \mathbf{E} = -\frac{1}{c}\frac{\partial \mathbf{B}}{\partial t}$$
$$\nabla \cdot \mathbf{B} = 0, \qquad \nabla \times \mathbf{B} = \frac{4\pi}{c}\mathbf{J} + \frac{1}{c}\frac{\partial \mathbf{E}}{\partial t}$$

The Schrödinger equation for a particle of mass $m$ in potential $V$ is

$$i\hbar \frac{\partial \Psi}{\partial t} = -\frac{\hbar^2}{2m}\nabla^2 \Psi + V\Psi$$

and the time-independent version $\hat{H}\psi = E\psi$ with Hamiltonian $\hat{H} = -\frac{\hbar^2}{2m}\nabla^2 + V$ has eigenvalues $E_n$ forming the energy spectrum.

Einstein's field equations of general relativity:

$$R_{\mu\nu} - \frac{1}{2}R\,g_{\mu\nu} + \Lambda\, g_{\mu\nu} = \frac{8\pi G}{c^4}\, T_{\mu\nu}$$

where $R_{\mu\nu}$ is the Ricci tensor, $R = g^{\mu\nu}R_{\mu\nu}$ is the scalar curvature, $g_{\mu\nu}$ is the metric tensor, $\Lambda$ is the cosmological constant, and $T_{\mu\nu}$ is the stress–energy tensor.

Complex Analysis

A function $f : \C \to \C$ is holomorphic on a domain $\Omega$ if $\bar{\partial} f = 0$, where $\bar{\partial} = \frac{1}{2}\left(\frac{\partial}{\partial x} + i\frac{\partial}{\partial y}\right)$. Equivalently, $f$ satisfies the Cauchy–Riemann equations:

$$\frac{\partial u}{\partial x} = \frac{\partial v}{\partial y}, \qquad \frac{\partial u}{\partial y} = -\frac{\partial v}{\partial x}$$

where $f = u + iv$. Cauchy's integral formula gives the value of $f$ at any point $z_0$ inside a simple closed contour $\gamma$:

$$f(z_0) = \frac{1}{2\pi i} \oint_\gamma \frac{f(z)}{z - z_0}\,dz$$

and its $n$-th derivative is $f^{(n)}(z_0) = \frac{n!}{2\pi i} \oint_\gamma \frac{f(z)}{(z - z_0)^{n+1}}\,dz$. A function with an isolated singularity at $z_0$ has a Laurent expansion

$$f(z) = \sum_{n=-\infty}^{\infty} a_n (z - z_0)^n, \qquad a_n = \frac{1}{2\pi i}\oint_\gamma \frac{f(z)}{(z - z_0)^{n+1}}\,dz$$

The coefficient $a_{-1} = \operatorname{Res}(f, z_0)$ is the residue, and the residue theorem states $\oint_\gamma f(z)\,dz = 2\pi i \sum_k \operatorname{Res}(f, z_k)$. A useful application: $\int_0^\infty \frac{\sin x}{x}\,dx = \frac{\pi}{2}$, proved via the contour integral $\oint_\gamma \frac{e^{iz}}{z}\,dz$ over an indented semicircle.

The Riemann mapping theorem states that any simply connected domain $\Omega \subsetneq \C$ is biholomorphic to the unit disk $\mathbb{D} = \{z : |z| < 1\}$. The Schwarz–Christoffel formula maps $\mathbb{H} \to P$:

$$f(z) = A + C \int^z \prod_{k=1}^{n} (\zeta - x_k)^{\alpha_k - 1}\,d\zeta$$

Discrete Mathematics & Algorithms

The number of subsets of $\{1, 2, \ldots, n\}$ of size $k$ is the binomial coefficient $\binom{n}{k} = \frac{n!}{k!(n-k)!}$. The binomial theorem gives

$$(x + y)^n = \sum_{k=0}^{n} \binom{n}{k} x^k y^{n-k}$$

A graph $G = (V, E)$ has adjacency matrix $\mathbf{A} \in \{0,1\}^{n \times n}$ where $A_{ij} = 1$ iff $\{i, j\} \in E$. The number of walks of length $k$ from $i$ to $j$ is $(\mathbf{A}^k)_{ij}$. The chromatic polynomial $P(G, k)$ counts the number of proper $k$-colorings; for a tree on $n$ vertices, $P(T_n, k) = k(k-1)^{n-1}$.

The Master theorem for divide-and-conquer recurrences: if $T(n) = aT(n/b) + \Theta(n^c)$, then

$$T(n) = \begin{cases} \Theta(n^c) & \text{if } \log_b a < c \\ \Theta(n^c \log n) & \text{if } \log_b a = c \\ \Theta(n^{\log_b a}) & \text{if } \log_b a > c \end{cases}$$

For instance, merge sort has $T(n) = 2T(n/2) + \Theta(n)$, so $a = b = 2$, $c = 1$, $\log_2 2 = 1 = c$, giving $T(n) = \Theta(n \log n)$. Strassen's matrix multiplication achieves $T(n) = 7T(n/2) + \Theta(n^2)$, yielding $T(n) = \Theta(n^{\log_2 7}) \approx \Theta(n^{2.807})$.

The generating function for the Fibonacci numbers $F_n$ is

$$\sum_{n=0}^{\infty} F_n x^n = \frac{x}{1 - x - x^2}$$

and the closed form is $F_n = \frac{\varphi^n - \hat{\varphi}^n}{\sqrt{5}}$ where $\varphi = \frac{1 + \sqrt{5}}{2}$ and $\hat{\varphi} = \frac{1 - \sqrt{5}}{2}$. The number of binary trees with $n$ internal nodes is the Catalan number $C_n = \frac{1}{n+1}\binom{2n}{n} = \frac{(2n)!}{(n+1)!\,n!}$.

Display Specimens

Large operators & delimiters
$$\prod_{p \text{ prime}} \frac{1}{1 - p^{-s}} = \sum_{n=1}^{\infty} \frac{1}{n^s} = \zeta(s), \qquad \Re(s) > 1$$
$$\oint_{\partial D} f(z)\, dz = 2\pi i \sum_{k=1}^{n} \operatorname{Res}(f, z_k)$$
$$\left\| \sum_{k=1}^{n} f_k \right\|_p \leq \left( \sum_{k=1}^{n} \|f_k\|_p^p \right)^{1/p}$$
Matrices & systems
$$\det \begin{pmatrix} a & b & c \\ d & e & f \\ g & h & i \end{pmatrix} = a(ei - fh) - b(di - fg) + c(dh - eg)$$
$$\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} \cos\theta & -\sin\theta \\ \sin\theta & \cos\theta \end{pmatrix} \begin{pmatrix} x \\ y \end{pmatrix}$$
Multiline & aligned
$$\begin{aligned} \nabla \times (\nabla \times \mathbf{A}) &= \nabla(\nabla \cdot \mathbf{A}) - \nabla^2 \mathbf{A} \\ &= \nabla(\nabla \cdot \mathbf{A}) - \Delta \mathbf{A} \end{aligned}$$
$$\begin{aligned} e^{i\theta} &= \cos\theta + i\sin\theta \\ e^{-i\theta} &= \cos\theta - i\sin\theta \\ \cos\theta &= \frac{e^{i\theta} + e^{-i\theta}}{2} \\ \sin\theta &= \frac{e^{i\theta} - e^{-i\theta}}{2i} \end{aligned}$$
Fractions, roots, accents
$$\cfrac{1}{1 + \cfrac{1}{1 + \cfrac{1}{1 + \cfrac{1}{1 + \cdots}}}}$$
$$\sqrt{1 + \sqrt{1 + \sqrt{1 + \sqrt{1 + \cdots}}}} = \frac{1 + \sqrt{5}}{2} = \varphi$$
$$\hat{f}(\xi) = \int_{-\infty}^{\infty} f(x)\, e^{-2\pi i x \xi}\, dx, \qquad \tilde{f}(x) = \overline{f(-x)}$$

Complete Glyph Inventory

Single-letter accents

$\hat{a}\;\hat{f}\;\hat{x}\;\hat{y}\;\hat{A}\;\hat{F}$   $\tilde{a}\;\tilde{f}\;\tilde{x}\;\tilde{y}\;\tilde{A}\;\tilde{F}$   $\bar{a}\;\bar{f}\;\bar{x}\;\bar{y}\;\bar{A}\;\bar{F}$

$\dot{a}\;\dot{f}\;\dot{x}\;\dot{y}\;\dot{A}\;\dot{F}$   $\ddot{a}\;\ddot{f}\;\ddot{x}\;\ddot{y}\;\ddot{A}\;\ddot{F}$   $\vec{a}\;\vec{f}\;\vec{x}\;\vec{y}\;\vec{A}\;\vec{F}$

$\check{a}\;\check{f}\;\check{x}\;\check{y}\;\check{A}\;\check{F}$   $\breve{a}\;\breve{f}\;\breve{x}\;\breve{y}\;\breve{A}\;\breve{F}$   $\acute{a}\;\acute{f}\;\acute{x}\;\acute{y}\;\acute{A}\;\acute{F}$

$\grave{a}\;\grave{f}\;\grave{x}\;\grave{y}\;\grave{A}\;\grave{F}$

Wide accents (progressively wider content)

$\widehat{x}\quad \widehat{xy}\quad \widehat{xyz}\quad \widehat{xyzw}\quad \widehat{xyzwv}$

$\widetilde{x}\quad \widetilde{xy}\quad \widetilde{xyz}\quad \widetilde{xyzw}\quad \widetilde{xyzwv}$

$\overline{x}\quad \overline{xy}\quad \overline{xyz}\quad \overline{xyzw}\quad \overline{x+y+z+w+v}$

$$\overbrace{a + b + c}^{3} \qquad \overbrace{a + b + c + d + e}^{5} \qquad \overbrace{a_1 + a_2 + \cdots + a_n}^{n \text{ terms}}$$
$$\underbrace{x_1 + x_2 + x_3}_{3} \qquad \underbrace{x_1 + x_2 + \cdots + x_n}_{n \text{ terms}}$$
Accents on Greek letters

$\hat{\alpha}\;\hat{\beta}\;\hat{\lambda}$   $\tilde{\sigma}\;\tilde{\omega}$   $\bar{\mu}\;\dot{\theta}\;\vec{\rho}$

Regular (mathrm) — uppercase

$\mathrm{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Regular (mathrm) — lowercase

$\mathrm{a\;b\;c\;d\;e\;f\;g\;h\;i\;j\;k\;l\;m\;n\;o\;p\;q\;r\;s\;t\;u\;v\;w\;x\;y\;z}$

Regular (mathrm) — digits

$\mathrm{0\;1\;2\;3\;4\;5\;6\;7\;8\;9}$

Italic (math default) — uppercase

$A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z$

Italic (math default) — lowercase

$a\;b\;c\;d\;e\;f\;g\;h\;i\;j\;k\;l\;m\;n\;o\;p\;q\;r\;s\;t\;u\;v\;w\;x\;y\;z$

Italic (math default) — digits

$0\;1\;2\;3\;4\;5\;6\;7\;8\;9$

Bold (mathbf) — uppercase

$\mathbf{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Bold (mathbf) — lowercase

$\mathbf{a\;b\;c\;d\;e\;f\;g\;h\;i\;j\;k\;l\;m\;n\;o\;p\;q\;r\;s\;t\;u\;v\;w\;x\;y\;z}$

Bold (mathbf) — digits

$\mathbf{0\;1\;2\;3\;4\;5\;6\;7\;8\;9}$

Bold Italic (boldsymbol) — uppercase

$\boldsymbol{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Bold Italic (boldsymbol) — lowercase

$\boldsymbol{a\;b\;c\;d\;e\;f\;g\;h\;i\;j\;k\;l\;m\;n\;o\;p\;q\;r\;s\;t\;u\;v\;w\;x\;y\;z}$

Bold Italic (boldsymbol) — digits

$\boldsymbol{0\;1\;2\;3\;4\;5\;6\;7\;8\;9}$

Greek uppercase — upright

$\Gamma\;\Delta\;\Theta\;\Lambda\;\Xi\;\Pi\;\Sigma\;\Upsilon\;\Phi\;\Psi\;\Omega$

Greek uppercase — bold

$\boldsymbol{\Gamma}\;\boldsymbol{\Delta}\;\boldsymbol{\Theta}\;\boldsymbol{\Lambda}\;\boldsymbol{\Xi}\;\boldsymbol{\Pi}\;\boldsymbol{\Sigma}\;\boldsymbol{\Upsilon}\;\boldsymbol{\Phi}\;\boldsymbol{\Psi}\;\boldsymbol{\Omega}$

Greek lowercase — regular

$\alpha\;\beta\;\gamma\;\delta\;\epsilon\;\zeta\;\eta\;\theta\;\iota\;\kappa\;\lambda\;\mu\;\nu\;\xi\;\pi\;\rho\;\sigma\;\tau\;\upsilon\;\phi\;\chi\;\psi\;\omega$

Greek lowercase — bold

$\boldsymbol{\alpha}\;\boldsymbol{\beta}\;\boldsymbol{\gamma}\;\boldsymbol{\delta}\;\boldsymbol{\epsilon}\;\boldsymbol{\zeta}\;\boldsymbol{\eta}\;\boldsymbol{\theta}\;\boldsymbol{\iota}\;\boldsymbol{\kappa}\;\boldsymbol{\lambda}\;\boldsymbol{\mu}\;\boldsymbol{\nu}\;\boldsymbol{\xi}\;\boldsymbol{\pi}\;\boldsymbol{\rho}\;\boldsymbol{\sigma}\;\boldsymbol{\tau}\;\boldsymbol{\upsilon}\;\boldsymbol{\phi}\;\boldsymbol{\chi}\;\boldsymbol{\psi}\;\boldsymbol{\omega}$

Greek variant forms — regular

$\varepsilon\;\vartheta\;\varkappa\;\varpi\;\varrho\;\varsigma\;\varphi$

Greek variant forms — bold

$\boldsymbol{\varepsilon}\;\boldsymbol{\vartheta}\;\boldsymbol{\varkappa}\;\boldsymbol{\varpi}\;\boldsymbol{\varrho}\;\boldsymbol{\varsigma}\;\boldsymbol{\varphi}$

Blackboard bold — uppercase

$\mathbb{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Blackboard bold — lowercase (if available)

$\mathbb{a\;b\;c\;d\;e\;f\;g\;h\;i\;j\;k\;l\;m\;n\;o\;p\;q\;r\;s\;t\;u\;v\;w\;x\;y\;z}$

Calligraphic — uppercase

$\mathcal{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Fraktur — uppercase

$\mathfrak{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Fraktur — lowercase

$\mathfrak{a\;b\;c\;d\;e\;f\;g\;h\;i\;j\;k\;l\;m\;n\;o\;p\;q\;r\;s\;t\;u\;v\;w\;x\;y\;z}$

Script (mathscr) — uppercase

$\mathscr{A\;B\;C\;D\;E\;F\;G\;H\;I\;J\;K\;L\;M\;N\;O\;P\;Q\;R\;S\;T\;U\;V\;W\;X\;Y\;Z}$

Arithmetic

$+\;\; -\;\; \times\;\; \div\;\; \pm\;\; \mp\;\; \cdot\;\; \circ\;\; \star\;\; \ast\;\; \bullet$

Binary operations

$\oplus\;\; \otimes\;\; \odot\;\; \ominus\;\; \oslash\;\; \wedge\;\; \vee\;\; \cap\;\; \cup$

Relations

$=\;\; \neq\;\; <\;\; >\;\; \leq\;\; \geq\;\; \ll\;\; \gg\;\; \approx\;\; \sim\;\; \simeq\;\; \cong\;\; \equiv\;\; \propto$

$\prec\;\; \succ\;\; \preceq\;\; \succeq$

Set theory

$\in\;\; \notin\;\; \ni\;\; \subset\;\; \supset\;\; \subseteq\;\; \supseteq$

$\sqsubset\;\; \sqsupset\;\; \sqsubseteq\;\; \sqsupseteq$

Arrows

$\rightarrow\;\; \leftarrow\;\; \Rightarrow\;\; \Leftarrow\;\; \leftrightarrow\;\; \Leftrightarrow\;\; \mapsto$

$\hookrightarrow\;\; \hookleftarrow\;\; \uparrow\;\; \downarrow\;\; \updownarrow$

$\nearrow\;\; \searrow\;\; \nwarrow\;\; \swarrow$

$\longrightarrow\;\; \longleftarrow\;\; \Longrightarrow\;\; \Longleftarrow$

Logic

$\forall\;\; \exists\;\; \nexists\;\; \neg\;\; \land\;\; \lor\;\; \vdash\;\; \models\;\; \top\;\; \bot\;\; \vDash\;\; \Vdash$

Miscellaneous symbols

$\infty\;\; \partial\;\; \nabla\;\; \triangle\;\; \square\;\; \diamond\;\; \hbar\;\; \ell\;\; \wp\;\; \Re\;\; \Im\;\; \aleph\;\; \beth$

Large operators
$$\sum_{i=1}^{n} \qquad \prod_{i=1}^{n} \qquad \coprod_{i=1}^{n} \qquad \int_{a}^{b} \qquad \oint_{\gamma} \qquad \iint_{\Omega}$$
$$\bigcup_{i=1}^{n} \qquad \bigcap_{i=1}^{n} \qquad \bigoplus_{i=1}^{n} \qquad \bigotimes_{i=1}^{n} \qquad \bigvee_{i=1}^{n} \qquad \bigwedge_{i=1}^{n}$$
Dots

$a_1, a_2, \ldots, a_n \qquad a_1 + a_2 + \cdots + a_n$

$$\begin{pmatrix} 1 & 0 & \cdots & 0 \\ 0 & 1 & \cdots & 0 \\ \vdots & \vdots & \ddots & \vdots \\ 0 & 0 & \cdots & 1 \end{pmatrix}$$
Delimiters at multiple sizes

1x: $( ) \quad [ ] \quad \{ \} \quad \langle \rangle \quad | \quad \|$

$$2\text{x: } \left(\frac{a}{b}\right) \quad \left[\frac{a}{b}\right] \quad \left\{\frac{a}{b}\right\} \quad \left\langle\frac{a}{b}\right\rangle \quad \left|\frac{a}{b}\right| \quad \left\|\frac{a}{b}\right\|$$
$$3\text{x: } \left(\frac{\displaystyle\sum_{i=1}^{n} x_i}{\displaystyle\prod_{j=1}^{m} y_j}\right) \quad \left[\frac{\displaystyle\sum_{i=1}^{n} x_i}{\displaystyle\prod_{j=1}^{m} y_j}\right] \quad \left\{\frac{\displaystyle\sum_{i=1}^{n} x_i}{\displaystyle\prod_{j=1}^{m} y_j}\right\} \quad \left\langle\frac{\displaystyle\sum_{i=1}^{n} x_i}{\displaystyle\prod_{j=1}^{m} y_j}\right\rangle \quad \left|\frac{\displaystyle\sum_{i=1}^{n} x_i}{\displaystyle\prod_{j=1}^{m} y_j}\right| \quad \left\|\frac{\displaystyle\sum_{i=1}^{n} x_i}{\displaystyle\prod_{j=1}^{m} y_j}\right\|$$
Spacing and sizing — same formula at different sizes

Display style: $\displaystyle \sum_{k=0}^{\infty} \frac{x^k}{k!} = e^x$

Text style: $\textstyle \sum_{k=0}^{\infty} \frac{x^k}{k!} = e^x$

Script style: $\scriptstyle \sum_{k=0}^{\infty} \frac{x^k}{k!} = e^x$

Scriptscript style: $\scriptscriptstyle \sum_{k=0}^{\infty} \frac{x^k}{k!} = e^x$