+-----------------------------------------------------------------------------------+
|                  THE FILTERED PROBABILITY SPACE: (Ω, F, {F_t}, P)                 |
|                                                                                   |
|  [Physical Measure P] ---> Real-world dynamics: dS_t = μ S_t dt + σ S_t dW_t^P   |
|          |                                                                        |
|          |  Girsanov Theorem / Change of Measure (Radon-Nikodym Derivative)       |
|          |  dQ/dP = exp( -∫θ_s dW_s^P - 1/2 ∫θ_s^2 ds )                          |
|          v                                                                        |
|  [Risk-Neutral Measure Q] -> Risk-neutral dynamics: dS_t = r S_t dt + σ S_t dW_t^Q|
|          |                                                                        |
|          |  Fundamental Theorem of Asset Pricing (FTAP)                           |
|          |  No Arbitrage <==> Existence of Q                                      |
|          |  Market Completeness <==> Uniqueness of Q                              |
|          v                                                                        |
|  [Pricing Measure] ------> Derivative Value: V_0 = e^(-rT) E^Q[ Payoff(S_T) ]    |
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