Pairwise disjoint set proof (help)

  • Thread starter Thread starter Willy_Will
  • Start date Start date
  • Tags Tags
    Proof Set
AI Thread Summary
To prove that a subset T of a family D of pairwise disjoint sets is also pairwise disjoint, one can show that the intersection of any two elements x and y in T is empty. Since x and y are elements of T and thus also of D, and given that D is pairwise disjoint, their intersection must be the empty set. This confirms that T maintains the property of being pairwise disjoint. The proof is validated through the logical deduction that follows from the definitions of disjoint sets. The discussion concludes with agreement on the correctness of the proof approach.
Willy_Will
Messages
15
Reaction score
0
hello,

I really don't know how to proceed here, since I don't know very much about sets/family.

I want to prove that if Ð is a family of pairwise disjoint sets, and Ŧ is a subset of Ð, prove that Ŧ is also a family of pairwise disjoint sets.

Thanks in advance math gurus

William
 
Physics news on Phys.org
if x and y are elements of T, then they are elements of D. So what is xny? (n means intersection)
 
if x and y are elements of T, then they are elements of D. because T is a subset of D.

However, xny will be empty set, because they are also elements of D, and D is pairwise disjoint.

T is also pairwise disjoint.

Like that?
 
Precisely.
 
Thanks guys!
 
I was reading a Bachelor thesis on Peano Arithmetic (PA). PA has the following axioms (not including the induction schema): $$\begin{align} & (A1) ~~~~ \forall x \neg (x + 1 = 0) \nonumber \\ & (A2) ~~~~ \forall xy (x + 1 =y + 1 \to x = y) \nonumber \\ & (A3) ~~~~ \forall x (x + 0 = x) \nonumber \\ & (A4) ~~~~ \forall xy (x + (y +1) = (x + y ) + 1) \nonumber \\ & (A5) ~~~~ \forall x (x \cdot 0 = 0) \nonumber \\ & (A6) ~~~~ \forall xy (x \cdot (y + 1) = (x \cdot y) + x) \nonumber...

Similar threads

Replies
12
Views
2K
Replies
3
Views
2K
Replies
1
Views
1K
Replies
7
Views
2K
Replies
5
Views
2K
Replies
1
Views
2K
Replies
2
Views
2K
Back
Top