Flashcards
B8.2

Cards in this deck (51)
- 1Let {ℙ_𝘁:𝘁∈𝕋} be a consistent family of finite-dimensional distributions. State the Daniell-Kolmogorov Extension Theorem

- 2Let (X_t:t≤T) be a stochastic process defined on (Ω,ℱ,ℙ). State the Kolmogorov-Čentsov continuity criterion

- 3Fix a Brownian motion (B_t)_t≥0 on (Ω,ℱ,ℙ). Recall B_0=0. State Blumenthal's 0-1 law

- 4Let S_t:=sup_(u≤t)B_u. State and prove The reflection principle

- 5State Doob's maximal and L^p inequalities

- 6State Doob's Optional Stopping Theorem for discrete supermartingales (bounded case)

- 7Let{Y_k} be a family of random variables and suppose Y_k->Y_∞ in probability. State the Vitali convergence theorem

- 8Let (X_t:t≥0) be a martingale with right-continuous sample paths. State the Martingale Convergence Theorem

- 9Let (Y_n)_(n∈ℕ) be a uniformly integrable martingale with respect to the filtration (𝒢_n)_(n∈ℕ), and let Y_∞ be the almost sure limit of Y_n when n -> ∞. State Optional stopping for UI discrete time martingales.

- 10Let M,N be continuous local martingales and K,H be two measurable processes. State the Kunita-Watanabe inequality

- 11Let X^1,...X^d be continuous semimartingales and F:ℝ->ℝ a C^2 function. State Itô's formula

- 12Let M be a continuous local martingale starting at zero. State Lévy's characterisation of Brownian motion.

- 13Let M be an ({ℱ_t}_(t≥0),ℙ)-continuous local martingale with M_0=0 and _∞=∞ almost surely. State the Dambis-Dubins-Schwarz Theorem.

- 14Give the covariance function definition for a standard Brownian motion

- 15Define a standard real Brownian motion

- 16Define what it means for a class 𝒞 of random variables to be uniformly integrable

- 17Define the quadratic co-variation between two continuous local martingales M and N

- 18Let M be a continuous local martingale and K∈L^2_loc(M). Define K•M

- 19Suppose M,N∈ℋ^(2,c) and K∈L^2(M), H∈L^2(N). State the quadratic co-variation of K•M and H•N

- 20Let M be a continuous local martingale, M_0∈L^2. State and prove two TFAEs regarding the L^2 norm and the long term behaviour of the quadratic co-variation of M. State and prove something about M^2_t-_t in both cases

- 21Define a continuous martingale

- 22Let X be a random variable on the probability space (Ω,ℱ,ℙ) and 𝒢_1⊆𝒢_2⊆ℱ. State the tower property of conditional expectation

- 23Define the natural filtration associated with the process X

- 24Let (Ω,ℱ,{ℱ}_(t≥0),ℙ) be a filtered probability space. Define a stopping time

- 25State Doob's Optional Theorem for martingales with continuous sample paths

- 26Define what it means for a function to be of finite variation and what it means for a stochastic process to be of finite variation

- 27Let X,Y be two stochastic processes defined on a common probability space (Ω,ℱ,ℙ). Define what it means for X to be a modification of Y and what it means to say X and Y are indistinguishable

- 28Prove that a continuous local martingale M with M_0=0 a.s., is a process of finite variation iff M is indistinguishable from 0

- 29State Fatou's Lemma in the context of expectation

- 30Let f:I->ℝ be a function defined on a subset I of [0,∞). For a

- 31State Doob's upcrossing lemma in discrete time

- 32State the moment generating function for a N(μ,σ^2) distribution1

- 33Prove that exp(λB_t-λ^(2)t/2) is a martingale if B is a standard Brownian motion (just expectation part)

- 34Let B^1 and B^2 be independent Brownian motions. State _t

- 35Let X=X_0+M+A be a continuous semimartingale. State an if and only if condition for X to be a submartingale

- 36State what it means for X_n->X a.s., in probability, in distribution, and in L^1

- 37Define what it means to say that a martingale is closed

- 38Let M be a continuous local martingale. State situations where M is a supermartingale and a UI martingale. Give stopping times that reduce M if M_0∈L^1. Comment on what type of process M^ρ is for any stopping time ρ

- 39Define what it means for for a process X to be adapted to a filtration {ℱ_t}_(t≥0)

- 40Define ℋ^(2,c)

- 41For a continuous local martingale M, define L^2_(loc)(M)

- 42Let B be a Brownian motion, for two times t and s, state 𝔼[B_tB_s]
![Let B be a Brownian motion, for two times t and s, state 𝔼[B_tB_s]](https://examtimeassets.s3.amazonaws.com/uploads/media/image/49616554/desktop_df726059-66c4-4a06-8898-5489190b66c8.jpg)
- 43Let M be a continuous martingale. Define the quadratic variation process _t associated with M_t

- 44What does it mean for a function to be càdlàg at a point t

- 45How can you compute 𝔼[X] if you already know 𝔼[X|Y]
![How can you compute 𝔼[X] if you already know 𝔼[X|Y]](https://examtimeassets.s3.amazonaws.com/uploads/media/image/49616579/desktop_c7c00df6-f87c-4107-80b2-07c3f87786d3.jpg)
- 46State where M is a continuous local martingale and A is a finite variation process

- 47State a theorem regarding the convergence of right-continuous supermartingales

- 48Assuming that X_t=exp(θB_t-θ^2t/2) defines a martingale, show that it converges to zero a.s.

- 49Let M∈ℋ^(2,c) and K∈L^2(M). State the steps to defining K•M

- 50Define a centred gaussian process

- 51Name 3 Brownian motions that can be derived from a standard real BM via symmetry, scaling, and time-reversal

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- uni Part B Flashcards on B8.2, created by Ben Tidswell on 15/04/2023.
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- Ben Tidswell
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