2025-08-01

opaque math notations

here are several categories of mathematical notation that are especially opaque or hard to track for someone from a computer science background, along with illustrative examples. these represent excellent test cases for stress-testing a referential, programming-inspired notation.

overloaded and omitted operators

example:

f(x + y) = f(x) + f(y)

problems:

  • + may mean real addition, group operation, vector addition, etc.
  • function f might be a morphism, homomorphism, or arbitrary function.
  • no types or domains are specified.

implicit quantification

example:

∀ε > 0, ∃δ > 0, ∀x, |x - c| < δ ⇒ |f(x) - l| < ε

problems:

  • no indication of types (x, c, f, l).
  • scope nesting is unclear.
  • logical structure is compressed and non-linear.

index-heavy algebra and summation notation

example:

∑_{i=1}^{n} a_{ij} b_{jk}

problems:

  • index tracking is manual.
  • variable binding is implicit.
  • semantics are lost outside the matrix context.

category theory diagrams and composition notation

example:

f: a -> b, g: b -> c, h = g ∘ f

problems:

  • directional semantics depend on convention.
  • composition order (g ∘ f) is opposite of evaluation order.
  • diagrams are informal, often with no canonical syntax.

point-free notation

example:

(id × f) ∘ δ

problems:

  • no variables, so the dataflow is opaque.
  • requires fluency with combinators.
  • difficult to evaluate step-by-step.

multi-level operator precedence

example:

a + b * c^d / e - f

problems:

  • implicit precedence and associativity.
  • no parentheses, types, or grouping indicators.
  • meaning changes dramatically with minor edits.

set-builder notation

example:

{x ∈ ℝ | x² < 2}

problems:

  • semantics of | vs : varies by source.
  • logical interpretation (x² < 2) is implicit.
  • no binding or scoping shown explicitly.

ellipsis and notational shortcuts

example:

1 + 2 + ... + n

problems:

  • no defined semantics for ....
  • interpretation is context-sensitive.
  • not machine-readable.

generic maps without concrete definitions

example:

let φ: g -> h be a group homomorphism

problems:

  • no definition of φ, only type.
  • all behavior is inferred from "homomorphism".
  • mapping rules are abstracted away.

use of symbols for concepts without clear anchoring

example:

ℒ(x, y), hom(x, y), ⟨x, y⟩, [x]_∼

problems:

  • notation depends on domain-specific conventions.
  • no universal syntax for defining these constructs.
  • requires extensive background knowledge to interpret. would you like to prototype referential rephrasings for one or more of these cases?