Calculating sup, inf, limsup, liminf, and limit points of a sequence

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The discussion focuses on calculating the supremum, infimum, limit superior, limit inferior, and limit points of the sequence defined by x_n = 1/n + (-1)^n. The user initially calculated the limit points as 1 and -1, with limsup as 1 and liminf as -1, while questioning their sup and inf values. Feedback indicates that the sup is correctly identified as 1.5, but the inf is incorrectly stated; the correct inf is -1. The user is reassured that their method of observing the sequence's behavior through its terms is valid.
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Question:
(I've got a few like this, so I'd like to know if I am doing them correctly.)

Compute the sup, inf, limsup, liminf, and all the limit points of the following sequence x_1, x_2,... where

x_n = 1/n + (-1)^n

What I did was write down the first few terms to get an idea of the behavior of the sequence.
From this I found that the limit points were 1 and -1
limsup = 1
liminf = -1
sup = 1.5 (I think)
inf = 0 (I'm not sure)

I'm not so sure about the inf because I don't think inf = liminf is allowed, but in this case the lower endpoint and the liminf both equal -1, I think...

Did I determined these values by the correct method, or is there some formal way of which I am unaware to 'compute' these things?

Also, are my values correct?

thanks-a-bunch :smile:
 
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write out the first few terms of the sequence and watch the trend of the terms. Your inf is wrong. Your sup is fine.
 
So that would mean that my inf = -1, just like I thought it should be. :rolleyes:

Thanks a lot!
 
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