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by Ond
January 15th, 2008, 11:05 am
Forum: Brainteaser Forum
Topic: two envelopes non paradox
Replies: 14
Views: 67828

two envelopes non paradox

praveensinghania:There is no paradox in this example and there exists an optimal strategy. I have explained everything above. I can help you out if you dont understand the formulas.
by Ond
January 10th, 2008, 1:50 pm
Forum: Brainteaser Forum
Topic: two envelopes non paradox
Replies: 14
Views: 67828

two envelopes non paradox

<t>First we need to solve the distibutions.f(x)=1 uniformly on [0,1]let Y=X^2F_Y(y)=P(Y<=y)P(X^2<=y)=P(X<=sqrt(y))=F_X(sqrt(y))differation yields f_Y(y)=f_x(sqrt(y))*1/(2*sqrt(y))=1/(2*sqrt(y)) , 0<y<1(and f_Y(y)=0 otherwise)-------------------------Lets say I see the number on the first paper is z....
by Ond
January 10th, 2008, 9:31 am
Forum: Brainteaser Forum
Topic: Google Interview Question
Replies: 9
Views: 67458

Google Interview Question

If you open the book and all the names are before ostark in alphabetical order:you tear out all the pages on the left side and the close the book and repeat.If you open the book and all the names are after ostark. You tear out all the pages on the right side...Continue until you find Ostark.
by Ond
February 3rd, 2005, 8:07 am
Forum: Book And Research Paper Forum
Topic: R.Litterman's papers
Replies: 30
Views: 204813

R.Litterman's papers

<t>Hi I would be very greatful if someone could send me a copy of "A Demystification of the Black-Litterman Model: Managing Quantitative and Traditional Construction". To moomin-----------------There is something very odd about my PM box. I cannot send private messages... : (Other functionalites on ...
by Ond
November 18th, 2004, 4:16 pm
Forum: Student Forum
Topic: Time series and correlation
Replies: 2
Views: 169192

Time series and correlation

I have time series of different length and need to a calculate a correlation between all of these assets.The problem is to get a good estimate and a positive semidefinite matrix. Any suggestions?
by Ond
August 5th, 2004, 10:32 pm
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

<t>QuoteOriginally posted by: alexandreCThe concept is that there are four states A, B C and D, with the following transition rules:A<-->B<-->C<-->D <-->A(for example, A= 11 B=10 C=00 and D=01 where 1 stands for ON and 0 for off.)There shall be 4 comandments: 1. Only the master is allowed to make th...
by Ond
August 5th, 2004, 9:48 pm
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

<t>I´m sorry but I think I have to make you disappoited alexandreC. Example1= the leader2= They guy who switch twice3-20 = the restThe switches start in position A.this is the order of the people who enter the room.1.2.2.2.1.2.2.2.1.3.3.3.1.4.4.4.1...19.19.19.1the leader has counted to 20 but nr 20 ...
by Ond
August 5th, 2004, 1:31 pm
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

<t>QuoteOriginally posted by: zerdnai am extremely dense in the morning. The problem with flipping counting switch only on the first entrance by non-leaders was that after 19 counts the leader has to make a decision whether to wait until 20 counts in case the switch was on initially, and he could be...
by Ond
August 5th, 2004, 11:48 am
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

<t>Is 18 OFF switches a typo? If you said 38 I would agree. Congratulations! You will be released from the prison. This means that the Leader has to enter the room at least 38 times. It works but it will take alot of time.Are you a swedish?---------------------------------There exist a strategy wher...
by Ond
August 5th, 2004, 8:05 am
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

<t>The prisoners have no sense of time. They dont even know if any time elapsed since they entered the room last time if the switches are in the same position as they left them. They have no idea if they are the first or last to enter the room. The one minute thingy is just for evaluation of the pro...
by Ond
August 4th, 2004, 6:22 pm
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

Ok its a start, but the switches start in a random position. So the present version of the algorithm does'nt work. Also remember that they must flip one and only one switch each time they enter the room.
by Ond
August 4th, 2004, 8:20 am
Forum: Brainteaser Forum
Topic: Jailbreak
Replies: 15
Views: 182446

Jailbreak

<t>Jailbreak20 men are arrested in a somewhat lawless country, for a crime they did not commit. They will be found guilty of these trumped up charges, but the judge, being a good man at heart, gives them a one-off chance to win their freedom. They will be kept in individual cells in a particular pri...
by Ond
July 22nd, 2004, 4:07 am
Forum: Off Topic
Topic: holdem poker
Replies: 4
Views: 181585

holdem poker

I not sure I understand your question. If I put the word change in your sentence the answer would be no the odds for you does'nt change if more people join the table, but it's more likely that someone else got a pair.
by Ond
July 12th, 2004, 9:02 pm
Forum: Programming and Software Forum
Topic: Matlab
Replies: 2
Views: 182843

Matlab

I have all the toolboxes but I only use the optimization toolbox and sometimes the statistics toolbox. There are some financial toolboxes but they are not very useful. You will end up implementing your own functions anyways.
by Ond
June 15th, 2004, 8:58 pm
Forum: Off Topic
Topic: Euro 2004 predictions
Replies: 36
Views: 193742

Euro 2004 predictions

<t>QuoteOriginally posted by: etalFrom performance of the first round, the conclusion I draw is that SPAIN is the best team, with Czech Rep. to be the next one.Ok they where good. But the strongest preformance whereSweden vs Bulgaria 5-0(Spain vs Russia 1-0 and Czech Rep vs Lithuania 2-1)Bulgaria pl...