1. Let Y 0 , Y 1 , ... be a sequence of independent random variables, which are identically distributed as N(0, 1). Is the discrete-time stochastic process {X 0 , X 1 , ...} generated by the sums a...

1. Let Y₀, Y₁, ... be a sequence of independent random variables, which are identically distributed as N(0, 1). Is the discrete-time stochastic process {X₀, X₁, ...} generated by the sums

a martingale?

2. Let Y₀, Y₁, ... be a sequence of independent random variables with finite mean values E(Y_i). Is the discrete-time stochastic process {X₀, X₁, ...} generated by the sums