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A little brainteaser for all you 'elite' Kdice players out there :p
the brain wrote
at 2:34 PM, Thursday April 23, 2009 EDT
Ok, this is given: you are playing a 1vs1 version of kdice with only 2 lands. Each player starts with 2 dice.
You are the first to take a turn. Assuming that your opponent will play optimally, what is your best move? (attack 2vs2, wait for an 8 stack, or maybe something else? :D)

I have a statistical proof of the best strategy, I just thought it might be an interesting challenge for you people who claim to 'know' the game ;).
(And yes, I know that this is hardly a realistic situation, but if you give it a try you might appreciate the complexity of the statistics involved)

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skrumgaer wrote
at 7:07 PM, Thursday April 23, 2009 EDT
You should attack approximately 1% of the time.

Let p1 be the probability that player 1 will attack. Let p2 be the probability that player 2 will counterattack. Then player 1's expected payoff would be p1q1 + (1-p1)(1-p2q2) where q1 and q2 are the probabilities of winning the particular attacks. Take the derivative of this and set to zero and you have

q1 = (1 - p2)q2

Likewise for player 2 (remember, both are optimizing) we will have

q2 = (1- p1)q3 where q3 is the probability that player 1 will win the counter-counter attack.

Now let both players have the same p. (An approximation). Then,

q1 = (1 - p)^2q3

or

p = 1 - sqrt(q1/q3)

Now for a 2 v 2, q1 = .44, and for a 3 v 3, q3 = .45, so the value of p is

p = 1 - sqrt (.44/.45)

which is approximately 1 - .99

so player 1 should attack 1 percent of the time and not attack 99 percent of the time.
skrumgaer wrote
at 7:38 PM, Thursday April 23, 2009 EDT
I goofed with a parenthesis. The solution is the smaller root of a quadratic equation and is approximately 19%.
inty wrote
at 1:15 AM, Friday April 24, 2009 EDT
lol kdice.


wiggin1 wrote
at 2:28 AM, Friday April 24, 2009 EDT
Skrum, what are you talking about... given a specific situation, there must be a best move, either attack or don't. It can't be best to attack 19% of the time in that situation.

montecarlo wrote
at 7:58 AM, Friday April 24, 2009 EDT
after reading your post, wiggin, i thought, hmmm, theres the right answer! but it still bugged me (cus i hate admitting defeat, im such a cocky sob).

but in the shower this morning i started thinking again about it. and i realized the assumption your 70.32 answer is based off of: that you are playing a conservabot. sure, if you assume that the bot will only attack if he has 8+6, then the best plan is to 2v2 and 8v8 him asap and you have a 70.32 chance of winning.

however, you cant assume anything about your opponent, that he will be dumb. i mean, if you were rolling against me, wiggin, and you lost your initial 2v2... why would i just sit and stack to 8+6? because then i would hold the advantage (according to you, a 70.32 advantage). so i should 2v2 and 8v8 you asap. but wait, as soon as i lose my 2v2, you would hold the 70.32 advantage, and no way would you forfeit that and wait for 8+6.

see what im saying? you need to visualize playing against a mirrorbot, not a conservabot. this bot is as genius as you.

so, in the end, you have a small range of outcomes: 2v2 ad infinitum for a slightly lower chance of winning, or 8+6v8+6 ad infinitum for a slightly higher chance of winning.

...

right?
wiggin1 wrote
at 8:40 AM, Friday April 24, 2009 EDT
Yes, I see what you are saying.

Let us instead assume I play a wiggin1-bot.
The wiggin1-bot 2v2s if possible, and if it's behind it 8v8s as soon as it can.

Again now the best move is to 2v2. Stacking to 8+6 is not an option, since it will 8v8 me before that. The bastard.
wiggin1 wrote
at 9:01 AM, Friday April 24, 2009 EDT
(Actually if you are playing 2nd against an optimal opponent, except he doesn't 2v2, then it's best to wait until 8+3 before 8v8ing him. Maybe he will lose the 8v5.)
Sliver Queen wrote
at 9:09 AM, Friday April 24, 2009 EDT
assuming that both players are playing optimally, they would, of course, be mirror images of each other.

another thought: if someone knew that you were going to 8v8 them and have a better opportunity to 8v8, why wouldn't they 7v7? then the whole chain breaks down and you are back the 2v2 which i think is pareto optimal.
skrumgaer wrote
at 9:57 AM, Friday April 24, 2009 EDT
wiggin1:

Consider bluffing in poker. If you bluff all the time, you lose too many chips. If you never bluff, the other bettors will drop out if you bet high on a good hand. So you have to bluff a percentage of the time, in a way that is not predictable by the other players.
wiggin1 wrote
at 10:13 AM, Friday April 24, 2009 EDT
Yes, because poker is a game of incomplete information. Unlike kdice.
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