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Leonardi.DB
a logical geometry project

Opposition, Obversion, and Duality (1993), p. 107
by Simons, Peter

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
Square (regular)
Colinearity range
0
Coplanarity range
0
Cospatiality range
0
Representation of contradiction
By central symmetry

Graph structure

I
  • Contradiction with E
  • Subcontrariety with O
  • Subalternation from A
E
  • Contradiction with I
  • Contrariety with A
  • Subalternation to O
O
  • Contradiction with A
  • Subcontrariety with I
  • Subalternation from E
A
  • Contradiction with O
  • Contrariety with E
  • Subalternation to I

Vertex description

Conceptual info
No
Mnemonic support (AEIO, purpurea ...)
Yes
Form
none
Label type
symbolic
Symbolic field
logic
Contains partial formulas or symbols
Yes
Logical system
syllogistics

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
symbolic
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 in Polish notation.

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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