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Explicit formula of boundary crossing probabilities for continuous local martingales to constant boundary

Yoann Potiron

Abstract

An explicit formula for the probability that a continuous local martingale crosses a one or two-sided random constant boundary in a finite time interval is derived. We obtain that the boundary crossing probability of a continuous local martingale to a constant boundary is equal to the boundary crossing probability of a standard Wiener process to a constant boundary up to a time change of quadratic variation value. This relies on the constancy of the boundary and the Dambis, Dubins-Schwarz theorem for continuous local martingale. The main idea of the proof is the scale invariant property of the time-changed Wiener process and thus the scale invariant property of the first-passage time. As an application, we also consider an inverse first-passage time problem of quadratic variation.

Explicit formula of boundary crossing probabilities for continuous local martingales to constant boundary

Abstract

An explicit formula for the probability that a continuous local martingale crosses a one or two-sided random constant boundary in a finite time interval is derived. We obtain that the boundary crossing probability of a continuous local martingale to a constant boundary is equal to the boundary crossing probability of a standard Wiener process to a constant boundary up to a time change of quadratic variation value. This relies on the constancy of the boundary and the Dambis, Dubins-Schwarz theorem for continuous local martingale. The main idea of the proof is the scale invariant property of the time-changed Wiener process and thus the scale invariant property of the first-passage time. As an application, we also consider an inverse first-passage time problem of quadratic variation.
Paper Structure (26 sections, 42 theorems, 214 equations)

This paper contains 26 sections, 42 theorems, 214 equations.

Key Result

Lemma 2.1

We obtain a Levy distribution with $P_g^W (0) = 0$, $f_g^W (0) = 0$,

Theorems & Definitions (114)

  • Definition 2.1
  • Definition 2.2
  • Lemma 2.1
  • Example 1
  • Proposition 2.1
  • Theorem 2.3
  • Corollary 2.1
  • Definition 2.4
  • Definition 2.5
  • Lemma 2.2
  • ...and 104 more