Why the Logical Hexagon? (2012), p. 71
by Moretti, Alessio
Copyright according to our policy
Caption
- Some “extensions” of the square of opposition
- Aristotelian family
- Sigma-6 Ladder
- Boolean complexity
- 7
- Number of labels per vertex (at most)
- 0
- Uniqueness of the vertices up to logical equivalence
- Yes
- Errors in the diagram
- Yes
- Shape
- Rectangle (irregular)
- Colinearity range
- 0–4
- Coplanarity range
- 0
- Cospatiality range
- 0
- Representation of contradiction
- By central symmetry
Logic
Geometry
- Conceptual info
- Yes
- Mnemonic support (AEIO, purpurea ...)
- No
- Form
- dots
- Label type
- none
- Contains definitions of relations
- No
- Form
- solid lines
- Has arrowheads
- Yes
- Overlap
- No
- Curved
- Yes
- Hooked
- No
- As wide as vertices
- No
- Contains text
- No
- Label type
- none
Vertex description
Edge description
- Diagram is colored
- No
- Diagram is embellished
- No
Style
Additional notes
- The diagram displayed is a sigma-6 ladder. It is ascribed to Celaya. However, the actual diagram in Celaya is a sigma-5 diagram (since it contains two pairs of equivalent formulas) which contains four unconnected pairs; it is thus certainly not a sigma-6 ladder.