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by exotica
December 18th, 2008, 7:38 am
Forum: Technical Forum
Topic: What is the model
Replies: 14
Views: 52918

What is the model

<t>TeaMaster,I'm not sure I correctly understand your point 1. HW model for instance can produce negative rates and should therefore be able to handle such a situation. If you want to calibrate it, what you actually need is probably swaption prices, which remain perfectly defined even with negative ...
by exotica
December 10th, 2008, 8:11 am
Forum: Student Forum
Topic: Ito Integrals
Replies: 4
Views: 47946

Ito Integrals

Take for instance W_T, then int_0^T W_T dW_s = W_T int_0^T dWs=W_T^2 whose expectation is T.
by exotica
December 10th, 2008, 8:09 am
Forum: Student Forum
Topic: Ito Integrals
Replies: 4
Views: 47946

Ito Integrals

by exotica
December 6th, 2007, 8:26 am
Forum: Brainteaser Forum
Topic: Expected drawdown of an n-step random walk
Replies: 5
Views: 63938

Expected drawdown of an n-step random walk

You might find this reference useful. I think it answers your question in the case of a brownian motion.here
by exotica
October 29th, 2007, 7:59 am
Forum: Student Forum
Topic: Is W(t)^3 Martingale
Replies: 10
Views: 67281

Is W(t)^3 Martingale

<t>Shisha,What Clopinette wants to say is that a martingale can have a mean different from 0. If you need an example, take M_t=a+W_t, where W_t is a standard brownian motion. Then M_t is a martingale: indeed E(M_t|F_s)=a+E(W_t|F_s)=a+W_s=M_s, with s<t, but E(M_t)=a, which can take any value you want...
by exotica
September 28th, 2007, 1:32 pm
Forum: Brainteaser Forum
Topic: Limit of a sequence
Replies: 13
Views: 67783

Limit of a sequence

<t>I'm afraid this is still incorrect. 1+1/n converges to 1, but (1+1/n)^n does not converge to 1...We have log(1+n)/log(n) = 1 + log(1+1/n)/log(n). Then, using log(1+x) ~x, we get (log(1+n)/log(n))^n= exp (n log(log(1+n)/log(n))) =exp (n log( 1 + log(1+1/n)/log(n) ) )~exp(n log(1+1/n)/log(n) ) ~exp...
by exotica
May 24th, 2007, 4:57 pm
Forum: Technical Forum
Topic: max-min
Replies: 3
Views: 71919

max-min

Thanks!
by exotica
May 22nd, 2007, 7:40 am
Forum: Technical Forum
Topic: max-min
Replies: 3
Views: 71919

max-min

<t>Hello,I'm curious to know if there are some references about options paying or where is the maximum of the asset over [0,T] and m_T the minimum.I assume the asset follows a Black-Scholes dynamics, with constant volatility and interest rate.I know the joint law of (M_T, m_T) can be written explici...
by exotica
March 26th, 2007, 1:22 pm
Forum: Technical Forum
Topic: Heston + Stochastic Rates
Replies: 12
Views: 89809

Heston + Stochastic Rates

Hi all,Does anyone know the precise reference for the paper of andreasen mentionned by piterbarg? I tried to google it but could only find a reference to an ICBI conference held in May 2006.Thanks in advance!
by exotica
March 21st, 2007, 7:47 am
Forum: Student Forum
Topic: Integrability
Replies: 4
Views: 76391

Integrability

In your example, Y and Z are not independent.
by exotica
January 15th, 2007, 9:16 am
Forum: Technical Forum
Topic: No arbitrage, risk-neutrality and the drift rate
Replies: 5
Views: 82779

No arbitrage, risk-neutrality and the drift rate

Perhaps it takes into account dividend yield, repo, etc.
by exotica
December 8th, 2006, 8:31 am
Forum: Technical Forum
Topic: appropriate number of timesteps in Heston
Replies: 14
Views: 89300

appropriate number of timesteps in Heston

<t>Hello,Clearly, the number of time steps has an influence on the result of your Monte Carlo simulation, as Rez explained, because if your discretization is not fine enough, it will not give a good approximation of what you're actually trying to compute (except for some specific cases like a browni...
by exotica
November 28th, 2005, 11:19 pm
Forum: Student Forum
Topic: independent increments and expectations
Replies: 3
Views: 129126

independent increments and expectations

<t>No.The increment is independent of but not . B_t is affected by the information in F_s because B_t is equal to B_s plus an increment (which happens to be independent of F_s). To be convinced just take the simplest case where your function is the identity. You have (martingale property of the brow...
by exotica
September 24th, 2005, 9:07 am
Forum: Student Forum
Topic: no arbitrage pricing VS equilibrium pricing
Replies: 3
Views: 136139

no arbitrage pricing VS equilibrium pricing

<t>Hi,Aaron, I'm not sure I understood your answer correctly or I'm missing something. In my opinion, no-arbitrage models don't ensure the existence of a hedge. Technically speaking, a model is arbitrage free is there exists a martingale measure. To have a (unique) hedging strategy, you require the ...
by exotica
June 1st, 2005, 5:46 pm
Forum: Student Forum
Topic: Variance of the Weiner Process
Replies: 5
Views: 147680

Variance of the Weiner Process

<t> I guess you're looking for a kind of physical explanation. You can probably say something like the brownian motion is the motion of a particle subject to a succession of many independent random shocks. So its behaviour is the result of a sum of independent random variables and, in virtue of the ...