Symmetric Difference if/then Proof

AI Thread Summary
The discussion centers on proving the statement that if X ⊕ Y = Y ⊕ X, then X must equal Y, where ⊕ denotes the symmetric difference of sets. Participants clarify that X and Y are sets and that ⊕ represents the symmetric difference, which is commutative. One contributor points out that the proof is flawed because the commutative property of symmetric difference implies that X ⊕ Y = Y ⊕ X holds true for any sets X and Y, without necessitating that X equals Y. The conversation emphasizes the need for a deeper understanding of the operations involved. Overall, the initial assertion about the equality of sets based on their symmetric difference is incorrect.
pingi
Messages
2
Reaction score
0
Hi there,

I'm trying to figure out proving the following:
if X oplus Y = Y oplus X then X = Y

In order to prove it, I need to use the symmetric difference associativity & other characteristics and identities.

Can you please give me a direction?
Please explain the answer as a teacher would, as my skills of proving this kind of arguments are poor.

Thanks! Pingi.
 
Physics news on Phys.org
What is oplus? Also what kind of things are X and Y (sets, logical variables, other things)?
 
Hi mathman,

Sorry for being unclear about my question and thanks for directing me!

1. X and Y are sets.
2. 'oplus' is an add symbol in circle - ⊕, used to describe the symmetric difference of the two sets (with the XOR operation).

Pingi.
 
If it is referring to the symmetric difference or to the exclusive or operations, then I actually don't believe the statement you are trying to prove is true. Both of these operations are commutative, which means that:

X "oplus" Y = Y "oplus" X

regardless of what X and Y are.

If "oplus" means something different, however, then please explain it in more depth.
 
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
7
Views
1K
Replies
6
Views
2K
Replies
19
Views
3K
Replies
9
Views
2K
Replies
3
Views
2K
Replies
4
Views
5K
Back
Top