Why the Logical Hexagon? (2012), p. 102
by Moretti, Alessio

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Caption

Sesmat’s unaccomplished $n$-opposition (1951)

Logic

Aristotelian family

Moretti-Pellissier Sigma-4

Boolean complexity

4–5

Number of labels per vertex (at most)

1

Uniqueness of the vertices up to logical equivalence

Yes

Errors in the diagram

No

Geometry

Shape

Square (regular)

Colinearity range

0

Coplanarity range

4

Cospatiality range

0

Representation of contradiction

By diametric opposition (but no central symmetry)

Vertex description

Conceptual info

Yes

Mnemonic support (AEIO, purpurea ...)

No

Form

none

Label type

generic placeholders

Edge description

Contains definitions of relations

No

Form

solid lines

Has arrowheads

No

Overlap

No

Curved

No

Hooked

No

As wide as vertices

No

Contains text

No

Label type

none

Style

Diagram is colored

No

Diagram is embellished

No