Girsanov theorem

E9114

Girsanov theorem is a fundamental result in stochastic calculus that describes how the dynamics of stochastic processes, particularly Brownian motion, change under an equivalent change of probability measure.

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Observed surface forms (1)

Surface form Occurrences
Girsanov’s theorem 1

Statements (49)

Predicate Object
instanceOf result in stochastic calculus
theorem
appliesTo Brownian motion
Itô processes
continuous-time stochastic processes
semimartingales
category theorems in probability theory
theorems in stochastic processes
concerns adapted processes
semimartingale characteristics
coreConcept Radon–Nikodym derivative
drift transformation
equivalent change of probability measure
exponential martingale
martingale measure
describes change of dynamics of stochastic processes under change of measure
how Brownian motion changes under an equivalent change of probability measure
enables construction of equivalent martingale measures
removal of drift from stochastic differential equations by measure change
field probability theory
stochastic analysis
stochastic calculus
formalizedIn measure-theoretic probability
generalizes change-of-measure techniques in classical probability
holdsOn filtered probability spaces
implies drift terms can be removed or introduced by changing measure
local martingales under one measure may become martingales under another
namedAfter Igor Vladimirovich Girsanov
relatedTo Cameron–Martin theorem
Doob–Meyer decomposition
Feynman–Kac formula
martingale representation theorem
requires Novikov condition or similar integrability condition
absolute continuity of measures on the underlying filtration
existence of an equivalent probability measure
statesThat a process that is Brownian motion under one measure becomes a Brownian motion with drift under another equivalent measure
under an equivalent change of measure the Brownian motion acquires a drift term
typicalAssumption Brownian motion with respect to a given filtration
integrability of the drift process
usedIn change from physical measure to risk-neutral measure
derivative pricing
filtering theory
large deviations theory
mathematical finance
risk-neutral valuation
stochastic control
uses Itô calculus
Radon–Nikodym derivative to define new measure
stochastic exponentials

Referenced by (5)

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Itô calculus relatedConcept Girsanov theorem
this entity surface form: Girsanov’s theorem
Cameron–Martin theorem relatedTo Girsanov theorem
Doob–Meyer decomposition relatedTo Girsanov theorem
Feynman–Kac formula relatedTo Girsanov theorem
Radon–Nikodym derivative usedFor Girsanov theorem