Let C (K ) denote a European vanilla Call option with strike price K. Assume that all options are identical except for strike price, and strike prices satisfy K1 < K2 < K3 and 2K2 = K1 + K3.
problem 1: ?What are the no-arbitrage lower bound, and the no-arbitrage upper bound, of the vertical spread:
C(K1) − C(K2)?
problem 2: Derive the functional relationship between the no-arbitrage values of the two vertical spreads:
C(K1) − C(K2) and C(K2) − C(K3).