What are the theoretical concept for the following terms in optiin pricing. 1.martingale property 2.discounted value of stock and portfolio are martingale. 3.what do we mean by discounted to what it refers to? 4.why we use radon Nikodem and girsanov theorems. 5.the concept of dividend. All should be theoretical ideas as all there in steven Shreve, just the real way of using those terms.