MathDB
2000 Guts #7: Expected value of monomial

Source:

October 12, 2014
algebrapolynomialprobabilityexpected value

Problem Statement

Suppose you are given a fair coin and a sheet of paper with the polynomial xmx^m written on it. Now for each toss of the coin, if heads show up, you must erase the polynomial xrx^r (where rr is going to change with time - initially it is mm) written on the paper and replace it with xrāˆ’1x^{r-1}. If tails show up, replace it with xr+1x^{r+1}. What is the expected value of the polynomial I get after mm such tosses? (Note: this is a different concept from the most probable value)