Game theory quiz

By:
AlixMartin  Get RSS Feed For Game theory quiz
Dated:
28 Oct, 2011
Tagged:
game theory , coaching
4 Comments

I recently started integrating some game theory lessons in my coaching. If you're a pro, you certainly already know all this. If you're an amateur, you might be better than some pros !

So here's a little quiz :

game tree

Here is a game played between a Red player and a Blue player. The Red player has a "polarized" range, the Blue player always has a bluff catcher. The pot is 1, and there is one pot sized bet left. It is not allowed to bet less than pot in this game.

- How many pure strategies are there for blue ? 

- How many pure strategies are there for red ?

- Are there some dominated lines ? 

- In the picture, blue can never bet. What would happen if he was allowed to bet after red checks ? 

- How often should blue call if he wants to be unexploitable ? What is the formula that gives this frequency ?

- How often should Red bluff ? What matters most : the ration between bets and checks when he has air, or the ratio between bluffs and value bets ?

- What is the formula that gives the "unexploitable" bluffing frequency ?

- If there is more money left and the only bet size allowed is an all-in overbet, should red luff less or more ? Should blue call less or more ?  

- The value of the game is the share of the initial pot a player guarantees himself when he plays a strategy. What is the value of the game for Red if he plays optimally ? How much of an equity boost does he get from bluffing ? What trick can be used to get the value of the game without making calculations ? 

Ok that's it for this post, I'll keep more complicated models, starting with the 2 street static game for future posts.

If you don't have a clue but want to learn more, you can go to wikipedia for the definition of the game theory concepts, and look at the different game theory videos I did in the Bluefire video archive.

Comments

  • RonSwanson
    RonSwanson (7 months ago)

    Im not sure if i got much of this right. I read half of math of poker about a year ago. Maybe its time to go over it again...

    - How many pure strategies are there for blue ?
    2

    - How many pure strategies are there for red ?
    2

    - Are there some dominated lines ?
    yes, red checking the nuts

    - In the picture, blue can never bet. What would happen if he was allowed to bet after red checks ?

    nothing because blue should never bet as his opponents range is nuts or air

    - How often should blue call if he wants to be unexploitable ? What is the formula that gives this frequency ?

    50%. Red can bluff risking 1 to win 1, if blue folds more than 50% red should never bluff, less than 50% and red should bluff evey air hand.

    - How often should Red bluff ? What matters most : the ration between bets and checks when he has air, or the ratio between bluffs and value bets ?

    red should bluff 0.5 times for every time he value bets, blue needs >33% equity to call. If red has the nuts 2/3 times he bets and air 1/3, blue is indifferent to calling

    - What is the formula that gives the "unexploitable" bluffing frequency ?
    make blue indifferent to calling. blue needs x% to call 3x - 1 = 0 therefore x = 1/3 therefore red should bluff 1 time for every 2 times he value bets

    - If there is more money left and the only bet size allowed is an all-in overbet, should red bluff less or more ? Should blue call less or more ?
    red bluff less / blue call less

    - The value of the game is the share of the initial pot a player guarantees himself when he plays a strategy. What is the value of the game for Red if he plays optimally ? How much of an equity boost does he get from bluffing ? What trick can be used to get the value of the game without making calculations ?

    Red
    redVB blue folds 0.2 x 0.5 x 1 = 0.1
    redVB blue calls 0.2 x 0.5 x 2 = 0.2
    redBluff blue calls 0.1 x 0.5 x -1 = -0.05
    redBluff blue folds 0.1 x 0.5 x 1 = 0.05
    red gives up = 0
    Total EV = 0.3

    Red only value bets (blue should fold everytime)
    redVB 0.2 x 1 = 0.2
    Total EV = 0.2

    Red gains 0.1 EV from bluffing.

  • AlixMartin
    AlixMartin (6 months ago)

    You got most of it right, but there are a couple wrong answers :

    - How many pure strategies are there for red ?
    - If there is more money left and the only bet size allowed is an all-in overbet, should red bluff less or more ?

    Also, making the other player indifferent to bluffing is a good trick to find the optimal strategies, but it can break down in some circumstances. Suppose for instance that red had 70 % nuts and 30 % air.

  • HA
    HA (6 months ago)

    - How many pure strategies are there for red ?
    4 - a)Always bet nuts, chk air b)Always bet nuts, bet air c)Always chk nuts, chk air d)Always chk nuts, bet air

    - If there is more money left and the only bet size allowed is an all-in overbet, should red bluff less or more ?
    Red bluff more, blue call less

  • slobasaurus
    slobasaurus (4 months ago)

    awesome.

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