dates intervals overlap
 

Hello,

I have the following situation:

column A column B

10.01.2010 15.01.2010
14.01.2010 21.01.2010
01.02.2010 15.02.2010
18.02.2010 20.02.2010
......


the series continue.

what I want to do is overlap all the intervals with a formula, and see if there are overlapping days. in my example, the answer should be "Yes" because the first and second interval overlap.
I found a way to overlap only 2 rows, but I want a way to overlap an indefinite number of rows.

any suggestions will be appreciated, even other idea of underlining the overlaps (graph, etc)