Limiting laws associated with Brownian motion perturbed by its maximum, minimum and local time, II

Bernard Roynette, Pierre Vallois, Marc Yor
2006 Studia scientiarum mathematicarum Hungarica (Print)  
Proof of Theorem 1.1 Let s > 0 and Γ s ∈ F s fixed. Using the definition of Q F x,t (Γ s ) and the Markov property we have : Property (1.7) and inequality (1.8) allow us to apply the dominated convergence theorem : 1.3 In this paper, we investigate four cases of examples involving respectively for (A t ) : • the unilateral maximum (resp. minimum) S t (resp. I t ) : We also consider, in the same case study the two-dimensional process (S t , t). • (L 0 t ; t ≥ 0) the local time at 0 of (X t ) t≥0
more » ... . • The triplet ((S t , I t , L 0 t ); t ≥ 0). • (D t ; t ≥ 0) the number of down-crossings of X from level b to level a. We observe that, in all cases, the function M s (y 0 , f ; y) may be written as : for some function M and some α ∈ R; in fact α = 0, except for the case 1, b), as shown below. Since s → M s (y 0 , f ; Y s ) is a P x0 -martingale, it is clear that s → M (f ; Y s )e αs is also a P x0 -martingale. The results are summarized in the following Table :
doi:10.1556/sscmath.43.2006.3.3 fatcat:qt23vlsj5jhkpbxr6i2ibb3e7y