Does Showing F(x+1/n)--->F(x) Prove Continuity to the Right for Any Sequence?

  • Thread starter quasar987
  • Start date
  • Tags
    Continuity
In summary, the conversation discusses the property of "continuity to the right" of the repartition function F, which states that for any sequence {a_n} that converges to x, F(a_n) also converges to F(x). The speaker questions whether the proof provided by their probability professor, which uses the 1/n sequence, is sufficient to prove this property. The other speaker explains that as long as the function F is increasing, the proof using the 1/n sequence is valid for any other sequence converging to 0 as well.
  • #1
quasar987
Science Advisor
Homework Helper
Gold Member
4,807
32
My probability professor proved the property of "continuity to the right" of the repartition function F by showing that F(x+1/n)--->F(x). But as I remember it, continuity to the right means that for any sequence {a_n} of elements of (x,+infty) that converges to x, F(a_n) converges to F(x). Is there some subtlety I'm not aware of by which showing F(x+1/n)--->F(x) is sufficient to show it works for any sequence?
 
Physics news on Phys.org
  • #2
Well, you are right.
If your professor's proof is correct, then his proof cannot essentially rely on other properties of the 1/n-sequence than that it converges to zero; i.e, that is, it is only the DISTANCE a given point x+1/n has from x that is relevant in the actual proof.

It might be that it is easiest to use 1/n as an EXAMPLE of a sequence, but the proof shouldn't crucially rest upon that particular choice.
 
Last edited:
  • #3
He agreed (by email) that it is insufficient to prove it for 1/n in the case of any function, but because the partition function F(x) is an increasing function, it is sufficient. Do you see why?
 
  • #4
Okay, note that since F is INCREASING, it means that the function values for any points squeezed in between 1/n and 1/(n+1) must be squeezed in between the function values F(1/n) and F(1/(n+1)).
Thus, any epsdilon/delta squeeze valid for the 1/n sequence must be valid for any other sequence converging to 0 as well, since its terms are necessarily squeezed in between the harmonic sequence terms.
 
  • #5
I see it thanks.
 

What does it mean for a function to have continuity to the right?

Continuity to the right means that a function is continuous at a specific point when approaching the point from the right side. In other words, the limit of the function from the right side is equal to the value of the function at that point.

Why is continuity to the right important in mathematics?

Continuity to the right is important because it ensures that a function is well-behaved and has no sudden jumps or breaks. This allows us to make accurate predictions and calculations using the function.

How can we determine if a function has continuity to the right?

To determine if a function has continuity to the right, we can use a variety of methods such as the limit definition of continuity, graphical analysis, and algebraic techniques like the Intermediate Value Theorem.

Can a function have continuity to the right but not to the left?

Yes, it is possible for a function to have continuity to the right but not to the left. This means that the limit of the function from the right side exists, but the limit from the left side does not exist or is not equal to the value of the function at that point.

What is the difference between continuity and continuity to the right?

Continuity refers to a function being continuous at a specific point, meaning that the limit of the function exists and is equal to the value of the function at that point. Continuity to the right specifically refers to the continuity of a function when approaching a point from the right side only.

Similar threads

Replies
1
Views
138
Replies
11
Views
975
Replies
3
Views
1K
Replies
1
Views
922
Replies
9
Views
882
Back
Top