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Leonardi.DB
a logical geometry project

Deontological Square, Hexagon, and Decagon: A Deontic Framework for Supererogation (2012), p. 202
by Joerden, Jan C.

Caption

The modallogical square

Legend

Logic

Aristotelian family
Classical Sigma-2
Boolean complexity
3
Number of labels per vertex (at most)
1
Uniqueness of the vertices up to logical equivalence
Yes
Errors in the diagram
No

Geometry

Shape
Rectangle (irregular)
Colinearity range
0
Coplanarity range
0
Cospatiality range
0
Representation of contradiction
By central symmetry

Vertex description

Conceptual info
No
Mnemonic support (AEIO, purpurea ...)
No
Form
none
Label type
linguistic
Language
English
Lexical field
modalities
Contains partial sentences or single words
Yes
Contains abbreviations
No

Edge description

Contains definitions of relations
No
Form
dotted lines
,
bold solid lines
,
solid lines
,
dashed lines
Has arrowheads
Yes
Overlap
No
Curved
No
Hooked
No
As wide as vertices
No
Label type
symbolic
,
none
Symbolic field
logic
Contains partial formulas or symbols
Yes
Logical system
propositional logic

Style

Diagram is colored
No
Diagram is embellished
No

Additional notes

The edges are labeled with propositional connectives corresponding to the Aristotelian relations (cf. Theorem 1 of Smessaert & Demey, 2014, Logical Geometries and Information in the Square of Oppositions, Journal of Logic, Language and Information 23 : 527 - 565).
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