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Leonardi.DB
a logical geometry project

Peri hermeneias (975–1025), fol. 39v
by Apuleius, Lucius

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

Vertex description

Conceptual info
Yes
Mnemonic support (AEIO, purpurea ...)
No
Form
square
Label type
symbolic
Symbolic field
logic
Contains partial formulas or symbols
Yes
Logical system
syllogistics

Edge description

Style

Diagram is colored
No
Diagram is embellished
No
Tags
diagram chasing

Additional notes

The letters A, B, C, D are used as we would later use A, E, I, O. Concretely: A stands for the universal affirmative statement, B stands for the universal negative statement, C stands for the particular affirmative statement, and D stands for the particular negative statement.

This diagram fully describes the relations between truth values of the four vertices. For example, starting from the vertical line at 12 o'clock and moving clockwise to the horizontal line at 3 o'clock, we read:

* C: si falsum est, astruitur B=> cf. contradiction between B and C
* D: si falsum est, destruitur B=> cf. subalternation from B to D
* A: si verum est, destruitur B=> cf. contrariety between A and B
* C: si verum est, destruitur B=> cf. contradiction between B and C
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