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Comment: Re:Solution (Score 1) 167

by abies (#46681073) Attached to: A Rock Paper Scissors Brainteaser

So you are saying that (some theoretical) game where I win 50% and draw 50% is equivalent to game where I win 75% and lose 25%, because in both cases difference between his win and my win are equivalent (50% = 50-0 or 50%=75-25)? And you are suggesting and amount best to bet on both games is the same?
Thats completely wrong. In 50%win/50tie situation I cannot lose, so I can bet at any distadvantage against him. With 75% win 25% lose I can bet at most triple of his bet to come equal. And replay on tie or lack of thereof doesn't matter, as long as we both get our money back on tie. Unless you come back with some strange rule that on tie we both lose money and it goes to the bank, but then it is more of 3-player game and not rock/scissors/paper in normal sense.

If you are still not convinced, please do a program which simulates a lot of random games with strategies above. You will see that amount of wins with 0.387 ratio of rock is higher than with 0.3333 ratio of rock. This is a real experiment, you can then correct your theories to fit it. Coming up with some arbitrary rules (taking difference between amount of wins ignoring ratio) which is contrary to common sense (as in my 50/0 75/25 example above) and contrary to experiment results (from the program I have written and you can write) is not a good science.

Comment: Re:Solution (Score 1) 167

by abies (#46675051) Attached to: A Rock Paper Scissors Brainteaser

I don't agree that x = 0. In that case, for 50% paper strategy for him, win is 1/3 vs 1/6 which is 2:1 in my favor. For 50% scissors strategy it is 1/2 versus 1/3 which is 3:2 in my favor. This means he WILL pick up 50% scissors in such case. Increasing x will reduce his winning chance. It will also increase his winning chance on paper strategy, but it will take longer to offset 2:1 disadvantage compared to 3:2.

Equation to solve is


gives x = -0.054093

which means rock of around 0.387.

Comment: Re:Solution (Score 1) 167

by abies (#46674429) Attached to: A Rock Paper Scissors Brainteaser

I still think that 38.4% rock and rest paper is better solution for 'free' player, than 1/3 rock and 2/3 paper if we assume that 'limited' player is very smart and knows 'free' player tactic upfront.

Can you tell me, what is the strategy which 'limited' player can take against 38.4% rock, rest paper which would lead to worse result for 'free' player than what you propose? I would suggest simulating the results before jumping to conclusion. I was also originally thinking that 1/3 rock is optimal, but increasing amount of rocks slightly, makes 50% scissors strategy less effective, but 50% paper strategy not good enough to offset paper wins on 'free' player part.

Comment: Re:Simple.... Odds are even (Score 1) 167

by abies (#46672379) Attached to: A Rock Paper Scissors Brainteaser

I'm getting better test results from having around 38.4% rock, rest paper. At this point his scissor and paper strategies become equal and I'm winning (assuming ties are repeated) 61.7% of cases instead of 60% of cases with 1/3 rock rest paper.

I think that trick is finding a place where any mixture of scissors or paper for him is equally bad. At this moment, his choices doesn't matter anymore (of course, unless he choses rock even at free choice). At 1/3 rock 2/3 paper, scissors are clearly better choice for him, so it is not a perfect place.

Comment: 38% rock and 62% paper ? (Score 1) 167

by abies (#46672297) Attached to: A Rock Paper Scissors Brainteaser

Ok, my current guess would be around 1/3 rock and 2/3 paper. Opponent cannot replicate this strategy, because of requirement of having at least 50% rock. If he goes 50% scissors, he will have 1/6 tie, 2/6 lose, 1/6 lose and 2/6 win, so 3:2 in my favor. With 50% paper, he gets 1/6 tie, 2/6 lose, 1/6 win, 2/6 tie, so 2:1 in my favor. 100% rock is obvious lose. I think that mixing scissors and paper will be clearly worse than pure scissors on his part (because with scissors, he has at least 2/3 chances of winning after he got a choice).

From random testing, it seems that optimal ratio of rock is around 38% (not 1/3). Around that point, pure paper and pure scissor strategies for opponent seems to get equal and I'm winning around 62% of cases.

There is probably some interesting math behind that...

Comment: Re:50% paper and 50% rock ? (Score 1) 167

by abies (#46672075) Attached to: A Rock Paper Scissors Brainteaser

Yes, you are right - paper will be 25% tie, 25% lose, ending up with 50% tie, 25% win, 25% lose, so still purely random.

I don't think that strategy we are looking for involves "reactions" - this can be always defeated by opponent which overguess you by one step. I would hope to find a strategy which would lead you to win > 50% even if opponent knows it (strategy itself, not the result of random choice at given stage).

Comment: 50% paper and 50% rock ? (Score 0) 167

by abies (#46670757) Attached to: A Rock Paper Scissors Brainteaser

Assuming we randomly use 50% paper and 50% rock, we get:
- on rounds he is forced to play rock, we get half victory and half tie, so 25% win, 25% tie so far
- on other rounds he can:
    - always use scissors, which will turn into our 25% win, 25% lose - we win overall, 50% win, 25% tie, 25% lose
    - always use rock, which will turn into our 25% tie, 25%win - we win overall, 50% win, 50% tie
    - always use paper, which will turn into 25% win, 25% lose - we win overall, 50% win, 25% tie, 25% lose
    - any kind of random mix of above, which can only move between results above, as our picks are completely random as well

So, he best strategy is to always play scissors or rock, for 50:25:25 result. If ties are repeated, we win 2 out of 3 times.

Any better strategy?

Comment: Let the best programmer win (Score 2) 246

I'm bit suprised at bad reputation HFT has at Slashdot. In many ways, it is very interesting subject for geeks - how often do you have to care about speed of light and benefits of straight-line microwave link over curvature-of-earth fiber... but most importantly, without HFT, you were able to win the market by either social networking (moving at the border of legalities regarding front running, insider trading etc), sheer amount of money or dumb luck. With HFT, you can win because you have best programmers.

I personally enjoy battle of programmers throwing algorithms against each other a lot more than shady agreements done by cabal of elitist traders agreeing over the phone whom to s***w over today. Maybe because I'm a programmer and I haven't managed to get into cabal of elite traders. I would expect most of Slashdot crowd to be on same side?

Or is it because somebody here had this wrong idea that before HFT a random person actually meant something on the market and was not being abused by Powers and that only after advent of HFT, poor private investors lost possibility to game the market? That 'technical analysis' actually meant more than 'how to win the lottery' systems?

This is war. Computers are rifles. Enemies are other big banks/hedges funds. Money is gunpowder. Stocks are bullets. And people... people are empty cases which get discarded from side of your rifle. And yes, HFT means that machine guns are now in play instead of bolt action rifles, but does it really matter matter to ejected cartridge...

Comment: Re:SAW XII: They Can Torture You Forever (Score 1) 357

by abies (#46604999) Attached to: Gunshot Victims To Be Part of "Suspended Animation" Trials

If I could only remember the name of the book... it was collection of short stories, centered about certain drug which was allowing people to transfer conciousness to next body. One of the stories was about usage of that by totalitarian government, which was catching political rebels and torturing them to death repeateadly transferring their mind to new body after each time - until they finally changed their opinions to the point of being able to convince everybody they have been reeducated.

Comment: Re:One side of the story (Score 1) 710

by abies (#46508629) Attached to: Prominent GitHub Engineer Julie Ann Horvath Quits Citing Harrassment

Ask yourself why you believe his side of the story first?

I don't. I'm saying that it is next to impossible for any company to stand against the woman playing the harrasement card, regardless of what was happening there. And reactions to saying "we should know the story as seen from other side" are "poor woman, it is obvious she is a victim, because she says so, we don't need to listen to other side, because woman is always a victim".

Shortest distance between two jokes = A straight line