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Leonardi.DB
a logical geometry project

The Mystery of the Fifth Logical Notion (Alice in the Wonderful Land of Logical Notions) (2020), p. 28
by Beziau, Jean-Yves

Logic

Aristotelian family
A Single PCD
Boolean complexity
2
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

Vertex description

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

Edge description

Contains definitions of relations
No
Form
solid lines
,
none
Has arrowheads
No
Overlap
No
Curved
No
Hooked
No
As wide as vertices
No
Contains text
No
Label type
none

Style

Diagram is colored
Yes
Diagram is embellished
No
Tags
Boolean closed
;
non-contingent formulas

Additional notes

This diagram is missing four relations; see here for the complete diagram.

Consider a domain $D$ = {a,b}, and the following relations over $D$:

* universality: {(a,a), (a,b), (b,a), (b,b)}
* emptiness: {}
* identity: {(a,a), (b,b)}
* difference: {(a,b), (b,a)}

These are binary relations over $D$, i.e. subsets of $D \times D$, or elements of $\wp(D \times D)$.

Note that universality and emptiness are resp. the top and bottom element of $\wp(D \times D)$.
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