Lévy Processes

Description: This quiz consists of 15 questions on Lévy Processes, a type of stochastic process with independent and stationary increments. These processes are widely used in various fields such as finance, physics, and biology.
Number of Questions: 15
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Tags: lévy processes stochastic processes independent increments stationary increments
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What is the defining characteristic of a Lévy process?

  1. Independent and stationary increments

  2. Continuous sample paths

  3. Gaussian distribution

  4. Finite variance


Correct Option: A
Explanation:

A Lévy process is characterized by its independent and stationary increments, meaning that the increments of the process over disjoint intervals are independent and identically distributed.

Which of the following is an example of a Lévy process?

  1. Brownian motion

  2. Poisson process

  3. Geometric Brownian motion

  4. Ornstein-Uhlenbeck process


Correct Option: B
Explanation:

The Poisson process is an example of a Lévy process, as it exhibits independent and stationary increments. It is commonly used to model the occurrence of events over time.

What is the characteristic function of a Lévy process?

  1. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1 - iux\right)\,\nu(dx)\right)$$

  2. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1\right)\,\nu(dx)\right)$$

  3. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1 + iux\right)\,\nu(dx)\right)$$

  4. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} + 1 - iux\right)\,\nu(dx)\right)$$


Correct Option: A
Explanation:

The characteristic function of a Lévy process is given by the formula $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1 - iux\right)\,\nu(dx)\right)$$, where $$\nu$$ is the Lévy measure.

What is the relationship between a Lévy process and its Lévy measure?

  1. The Lévy measure is the distribution of the jumps of the process.

  2. The Lévy measure is the distribution of the increments of the process.

  3. The Lévy measure is the distribution of the sample paths of the process.

  4. The Lévy measure is the distribution of the characteristic function of the process.


Correct Option: A
Explanation:

The Lévy measure $$\nu$$ is the distribution of the jumps of the Lévy process. It characterizes the frequency and magnitude of the jumps in the process.

Which of the following properties is not satisfied by a Lévy process?

  1. Independent increments

  2. Stationary increments

  3. Gaussian distribution

  4. Infinitely divisible distribution


Correct Option: C
Explanation:

Lévy processes do not necessarily have a Gaussian distribution. In fact, many Lévy processes, such as the Poisson process, have distributions that are far from Gaussian.

What is the relationship between a Lévy process and its drift and diffusion coefficients?

  1. The drift coefficient is the mean of the increments of the process.

  2. The diffusion coefficient is the variance of the increments of the process.

  3. The drift coefficient is the rate of change of the mean of the process.

  4. The diffusion coefficient is the rate of change of the variance of the process.


Correct Option: C
Explanation:

The drift coefficient $$\mu$$ of a Lévy process is the rate of change of the mean of the process, while the diffusion coefficient $$\sigma^2$$ is the rate of change of the variance of the process.

Which of the following is an application of Lévy processes?

  1. Modeling financial asset prices

  2. Modeling the arrival of customers in a queue

  3. Modeling the spread of diseases

  4. All of the above


Correct Option: D
Explanation:

Lévy processes have a wide range of applications, including modeling financial asset prices, the arrival of customers in a queue, the spread of diseases, and many other phenomena.

What is the relationship between a Lévy process and a Wiener process?

  1. A Wiener process is a special case of a Lévy process.

  2. A Lévy process is a special case of a Wiener process.

  3. A Wiener process and a Lévy process are independent.

  4. A Wiener process and a Lévy process are mutually exclusive.


Correct Option: A
Explanation:

A Wiener process, also known as Brownian motion, is a special case of a Lévy process with no jumps and a continuous sample path.

What is the characteristic function of a compound Poisson process?

  1. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1\right)\,\nu(dx)\right)$$

  2. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1 - iux\right)\,\nu(dx)\right)$$

  3. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} + 1 - iux\right)\,\nu(dx)\right)$$

  4. $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} + 1 + iux\right)\,\nu(dx)\right)$$


Correct Option: A
Explanation:

The characteristic function of a compound Poisson process is given by the formula $$\phi(u) = \exp\left(\int_\mathbb{R} \left(e^{iux} - 1\right)\,\nu(dx)\right)$$, where $$\nu$$ is the Lévy measure.

What is the relationship between a Lévy process and its generator?

  1. The generator is the infinitesimal generator of the process.

  2. The generator is the characteristic function of the process.

  3. The generator is the Lévy measure of the process.

  4. The generator is the distribution of the process.


Correct Option: A
Explanation:

The generator $$\mathcal{A}$$ of a Lévy process is the infinitesimal generator of the process, which is an operator that characterizes the infinitesimal behavior of the process.

Which of the following is a property of the generator of a Lévy process?

  1. It is a linear operator.

  2. It is a bounded operator.

  3. It is a positive operator.

  4. All of the above


Correct Option: D
Explanation:

The generator of a Lévy process is a linear, bounded, and positive operator.

What is the relationship between a Lévy process and its semigroup?

  1. The semigroup is the collection of transition probabilities of the process.

  2. The semigroup is the collection of characteristic functions of the process.

  3. The semigroup is the collection of generators of the process.

  4. The semigroup is the collection of Lévy measures of the process.


Correct Option: A
Explanation:

The semigroup $${P_t}_{t\ge0}$$ of a Lévy process is the collection of transition probabilities of the process, which describes the evolution of the process over time.

Which of the following is a property of the semigroup of a Lévy process?

  1. It is a strongly continuous semigroup.

  2. It is a Markov semigroup.

  3. It is a Feller semigroup.

  4. All of the above


Correct Option: D
Explanation:

The semigroup of a Lévy process is a strongly continuous, Markov, and Feller semigroup.

What is the relationship between a Lévy process and its associated measure?

  1. The associated measure is the distribution of the process.

  2. The associated measure is the characteristic function of the process.

  3. The associated measure is the Lévy measure of the process.

  4. The associated measure is the generator of the process.


Correct Option: A
Explanation:

The associated measure $$\mu$$ of a Lévy process is the distribution of the process, which describes the probability distribution of the process at any given time.

Which of the following is a property of the associated measure of a Lévy process?

  1. It is a probability measure.

  2. It is a tight measure.

  3. It is a Feller measure.

  4. All of the above


Correct Option: D
Explanation:

The associated measure of a Lévy process is a probability measure, a tight measure, and a Feller measure.

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