Tic: Relations & Sets: A Subset Possibility?

  • Thread starter Thread starter StIgM@
  • Start date Start date
  • Tags Tags
    Relations Sets
AI Thread Summary
A relation can indeed be a subset of another relation, as defined in set theory. The example given illustrates that the relational composition of X and Y can be a subset of Z if Z includes all pairs from that composition. The discussion emphasizes understanding the definitions of binary and n-ary relations. While some participants noted that the question resembles a homework query, they acknowledged the validity of the example provided. Overall, the conversation centers on the relationship between subsets and relations in set theory.
StIgM@
Messages
8
Reaction score
0
Hello guys,
I am new to this forum.

I have a question:
A relation can be subset of some other relation?

For example? I have the relations
X: A <---> B
Y: B <---> C
Z: A <---> C

X relational composition Y can be a subset of Z (if Z contains all the pairs of the composition)

Thanks in advance for your help

StIgM@
 
Physics news on Phys.org
A binary relation is a set R of pairs (x,y) such that (x,y) is in R if an only if x is related to y. If x and y are related we write xRy. In general, a n-ary relation in general is a set of n-tuples. A subset of a relation R is merely a subset of the set R.

In set theory we usually define a relation as an ordered triple (A,B,R), where R is a subset of A x B.
 
Ok, I get your meaning but you didn't give an answer to my example!

Do you know if this is correct?

For example? I have the relations
X: A <---> B
Y: B <---> C
Z: A <---> C

X relational composition Y can be a subset of Z (if Z contains all the pairs of the composition)
?
 
StIgM@ said:
Ok, I get your meaning but you didn't give an answer to my example!

Do you know if this is correct?

For example? I have the relations
X: A <---> B
Y: B <---> C
Z: A <---> C

X relational composition Y can be a subset of Z (if Z contains all the pairs of the composition)
?

This is not really the right place to post homework-style questions. Also Jarle's post contains the answer to your question in the clever wording of the definition. Good luck, welcome to the forum!
 
I was reading documentation about the soundness and completeness of logic formal systems. Consider the following $$\vdash_S \phi$$ where ##S## is the proof-system making part the formal system and ##\phi## is a wff (well formed formula) of the formal language. Note the blank on left of the turnstile symbol ##\vdash_S##, as far as I can tell it actually represents the empty set. So what does it mean ? I guess it actually means ##\phi## is a theorem of the formal system, i.e. there is a...

Similar threads

Replies
1
Views
2K
Replies
1
Views
1K
Replies
1
Views
2K
Replies
35
Views
4K
Replies
2
Views
2K
Replies
5
Views
2K
Replies
5
Views
2K
Back
Top