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Single Idea 9561

[filed under theme 5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic ]

Full Idea

Everything one needs to do with relations in mathematics can be done by taking a relation to be a set of ordered pairs. (Ordered triples etc. can be defined as order pairs, so that <x,y,z> is <x,<y,z>>).

Gist of Idea

The mathematics of relations is entirely covered by ordered pairs

Source

Charles Chihara (A Structural Account of Mathematics [2004], 07.2)

Book Ref

Chihara,Charles: 'A Structural Account of Mathematics' [OUP 2004], p.174


A Reaction

How do we distinguish 'I own my cat' from 'I love my cat'? Or 'I quite like my cat' from 'I adore my cat'? Nevertheless, this is an interesting starting point for a discussion of relations.


The 11 ideas with the same theme [role of terms which connect objects into relationships]:

De Morgan found inferences involving relations, which eluded Aristotle's syllogistic [De Morgan, by Hart,WD]
De Morgan started the study of relations and their properties [De Morgan, by Walicki]
The logic of relatives relies on objects built of any relations (rather than on classes) [Peirce]
Relations are functions with two arguments [Frege]
In 'Principia' a new abstract theory of relations appeared, and was applied [Russell/Whitehead, by Gödel]
All relations, apart from ancestrals, can be reduced to simpler logic [Quine]
We can use mereology to simulate quantification over relations [Lewis]
Relations need terms, so they must be second-order entities based on first-order tropes [Campbell,K]
A relation is either a set of sets of sets, or a set of sets [Burgess/Rosen]
The mathematics of relations is entirely covered by ordered pairs [Chihara]
'Before' and 'after' are not two relations, but one relation with two orders [Hossack]