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Leonardi.DB
a logical geometry project

Subalternation and existence presuppositions in an unconventionally formalized canonical square of opposition (2016), p. 203
by Jacquette, Dale

Caption

Unconventional logical square of opposition 1

Logic

Aristotelian family
Non-Sigma
Boolean complexity
4
Number of labels per vertex (at most)
3
Equivalence between (some) labels of the same vertex
No
Analogy between (some) labels of the same vertex
No
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
N.A.

Vertex description

Conceptual info
No
Mnemonic support (AEIO, purpurea ...)
Yes
Form
none
Label type
linguistic
,
symbolic
Language
English
Lexical field
syllogistics
Contains partial sentences or single words
No
Contains abbreviations
Yes
Symbolic field
logic
Contains partial formulas or symbols
Yes
Logical system
syllogistics
,
predicate logic

Edge description

Contains definitions of relations
No
Form
solid lines
,
none
Has arrowheads
Yes
Overlap
No
Curved
No
Hooked
No
As wide as vertices
No
Contains text
Yes
Label type
linguistic
Language
English
Contains partial sentences or single words
Yes
Contain abbreviations
No

Style

Diagram is colored
No
Diagram is embellished
No
Tags
existential import

Additional notes

The negation closure of this diagram is a Buridan sigma-4 (of Boolean complexity 4).

Note that $\exists x[Sx \to (\neg)Px]$ is not the correct formalization of the natural language statement `Some S is (not) P'.
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