Math — Visual Index

Find something that looks like your formula, then open the link beside it.

Basic symbols

I see something like…	Open
$a = b$ , $a \neq = b$ , $x \leq 10$ , $a := b$	Equality and comparison
$N$ , $Z$ , $R$ , $C$	Number sets
$x \in S$ , $A \cup B$ , $A \subseteq B$ , ${x \in S : P (x)}$	Sets
$\neg P$ , $P \land Q$ , $P \Rightarrow Q$ , $P ⟺ Q$	Logic
$\forall x$ , $\exists y$	Quantifiers
$x_{i}$ , $a^{n}$ , $i = 1, \dots, n$	Indices

Operators and values

I see something like…	Open
$\sum_{i = 1}^{n} a_{i}$ , $\prod_{i = 1}^{n} a_{i}$	Sums and products
$min S$ , $max_{i} x_{i}$	Minimum and maximum
$min_{x} f (x)$ versus $argmin_{x} f (x)$	min versus argmin
$⌈ x ⌉$ , $⌊ x ⌋$	Ceiling and floor
$∣ x ∣$ , $∣ S ∣$ , $∥ v ∥$	Bars and norms
$(a, b)$ , $[a, b]$ , $A [i]$ , $f (x)$	Brackets and intervals

Functions and optimization

I see something like…	Open
$f : A \to B$ , $x \mapsto f (x)$ , $g \circ f$	Functions
$f (x) = {\dots$	Piecewise definitions
$1_{P (x)}$ , $[P (x)]$	Indicator functions
$min_{x} f (x) s.t. g (x) \leq 0$	Optimization form
$min max \sum$ in one large formula	Worked optimization formula
$T (P)$ and path capacities	Capacity formula

Algebra and computer science

I see something like…	Open
$\frac{a}{b}$ , $a / b$ , a ratio	Fractions
$a = b + c \Rightarrow a - c = b$	Algebra transformations
$G = (V, E)$ , $u \sim v$ , $de g (v)$ , paths	Graph theory
$(a_{n})_{n \geq 0}$ , $a_{n} = a_{n - 1} + a_{n - 2}$	Sequences and recurrences
$O (n)$ , $O (n lo g n)$ , $Θ (n^{2})$	Complexity
$P (A)$ , $P (A ∣ B)$ , $E [X]$ , $Var (X)$	Probability
$x \leftarrow 5$ , `for`, `while`, `return`	Algorithms
$Σ^{*}$ , $ε$ , $L_{1} \cup L_{2}$	Formal languages
$Γ ⊢ e : τ$ , $e ⇓ v$ , $e [x := v]$	Types and programming languages

Proofs and statements

I see something like…	Open
“theorem”, “lemma”, “corollary”, “QED”	Proof vocabulary
contradiction, induction, counterexample	Proof styles
$P \Rightarrow Q$ , “if”, “only if”, “iff”	Necessary and sufficient
$:=$ , $\leq$ , $min$ , recurrence, cases	Equation styles
$:$ , $;$ , comma, $∣$ inside a formula	Formula punctuation

Help me read or write it

I need…	Open
$α$ , $β$ , $λ$ , $μ$ , $σ$ , $θ$	Greek letters
A step-by-step way to read a formula	Reading checklist
To watch one formula being decoded	Decoding example
`\sum`, `\frac`, `\begin{aligned}`	LaTeX cheat sheet
A template for analyzing a formula	Analysis template
The shortest summary of everything	One-page mental model

8 items under this folder.