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square

Represents an unfilled square shape commonly used in mathematical logic, proofs, and set theory.

Overview

Primarily employed in formal mathematics and logic to denote the end of a proof (as an alternative to QED), mark incomplete items, or represent operators in modal logic.

  • Frequently appears in academic papers and mathematical textbooks as a proof terminator
  • Used in modal logic to represent necessity operators
  • Common in set theory and abstract algebra for special operators
  • Often combined with other symbols to create more complex mathematical notation

Examples

Logical necessity operator in modal logic

□p  ⟹  p\square p \implies p 
\square p \implies p

Empty box in a mathematical proof

x+y=y+x□x + y = y + x \quad \square 
x + y = y + x \quad \square

Set of all possible worlds in modal logic

M={w∈W:□ϕ(w)}M = \{w \in W : \square\phi(w)\} 
M = \{w \in W : \square\phi(w)\}