Lim sup lim inf of rationals in [0,1]

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In summary, the limit supremum (lim sup) of the set of rationals in the closed interval [0,1] is the largest number that is a upper bound for the set, and the limit infimum (lim inf) is the smallest number that is a lower bound for the set. To prove the correct value for lim sup, you would need to show that the proposed value is an upper bound for the set and no number smaller than it is an upper bound. Additionally, finding the limit points of the set can help determine the correct value for lim sup.
  • #1
dopeyranger
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what is the lim sup of the set containing all rationals in the closed interval [0,1] ?
and what is the lim inf?

How do I prove that the value is correct?
 
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  • #2
dopeyranger said:
what is the lim sup of the set containing all rationals in the closed interval [0,1] ?
and what is the lim inf?

How do I prove that the value is correct?

Well, if you think the lim sup might be, for example, 2 [mind you, I'm not saying it is], you would have to show two things:

1. 2 is an upper bound for your set of numbers
2. No number less than 2 is an upper bound for your set of numbers.

In other words, you use the definition. What is your opinion in regard to 2 being the sup? And why? That might get you thinking about what you need to do.
 
  • #3
Have you found the limit points of the set of rationals in [0,1]?
 

FAQ: Lim sup lim inf of rationals in [0,1]

What is the definition of lim sup and lim inf of rationals in [0,1]?

The lim sup (limit superior) of a sequence of rational numbers in the interval [0,1] is the largest number that can be approached by the sequence from above. Similarly, the lim inf (limit inferior) is the smallest number that can be approached by the sequence from below.

How are lim sup and lim inf of rationals in [0,1] calculated?

To calculate the lim sup and lim inf of a sequence of rational numbers in [0,1], we take the supremum (or least upper bound) and infimum (or greatest lower bound) of the set of all numbers that appear in the sequence. The lim sup is always equal to or greater than the lim inf.

What is the role of the interval [0,1] in lim sup and lim inf of rationals?

The interval [0,1] serves as a boundary or range for the sequence of rational numbers. It restricts the values that can be approached by the sequence, making it easier to determine the lim sup and lim inf within a specific range.

How do lim sup and lim inf of rationals in [0,1] relate to the concept of limits?

The lim sup and lim inf of a sequence of rational numbers in [0,1] represent the largest and smallest values that the sequence can approach, respectively. This is similar to the concept of limits, where the limit of a sequence is the value that it approaches as the number of terms increases to infinity.

Are lim sup and lim inf of rationals in [0,1] always rational numbers?

No, the lim sup and lim inf of a sequence of rational numbers in [0,1] may not always be rational numbers. It depends on the sequence and the values that it approaches. In some cases, the lim sup and lim inf may be irrational numbers or even infinity.

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