Jean-Yves Beziau & Ioannis Vandoulakis 
The Exoteric Square of Opposition 
The Sixth World Congress on the Square of Opposition

The Square of opposition: Past, Present and Future.- Division of Entities and Foundations of Reality: Aristotle’s Ontological Square.- Logical Oppositions in Avicenna’s Hypothetical Logic.- Incommensurability and Inapplicability of the Squares of Opposition.- The square of opposition as a framework for Stephen Langton’s theological solutions.- The limits of the square – Hegel’s opposition to diagrams in its historical context.- Augustus De Morgan’s Unpublished Octagon of Opposition.- A Bitstring Semantic for Calculus CL.- Logical Diagrams, Visualization Criteria, and Boolean Algebras.- Turnstile Figures of Opposition.- The Naturalness of Jacques Lacan’s Logic.- On Modal Opposition within some Modal Discussive Logics.- On the Transformations of the Square of Opposition from the point of view of Institution Model Theory.- Color-Coded Epistemic Modes in a Jungian Hexagon of Opposition.- Many-valued logical hexagons in a 3-oppositional trisimplex.- Tri-Simplicial Contradiction: the Pascalian 3D Simplex and its Oppositional Tri-Segment.