# Down arrow? Probability question

1. Nov 24, 2006

### Office_Shredder

Staff Emeritus
A question on my probability problem set reads: If the sequence of events An is non-decreasing (i.e. An is a superset of An+1 for all n), prove the following

$$P[A_n] \downarrow P[\bigcap_{i=0}^\infty A_i]$$

I just need to know what the heck the down arrow means

2. Nov 25, 2006

### slearch

I think it means that the probabilities on the left are a non-increasing sequence converging to the number on the right (that's what you have to prove).