Example image of eyePlorer eyePlorer map for 'Entitative graph': Charles Sanders Peirce Formal system Graph (mathematics) Graph theory Logic Propositional calculus Syntax Curve Complement Logical disjunction Tautology (logic) First-order logic Formula Satisfiability and validity Dual Existential graph Normal modal logic G. Spencer-Brown Laws of Form Charles Hartshorne Paul Weiss (philosopher) Charles Sanders Peirce bibliography Logical graph Diagrammatic reasoning