12/07/2009

12-07-09 - Balancing Ranges

When you go to the bathroom, you should always turn on the fan. If you only turn on the fan when you're doing something stinky, you are creating a strong correlation between the external observable (fan on/off) and the internal hidden state (stinky). You can't hide the fan on/off state, so your goal is remove the correlation. You do this just by always turning on the fan.

In poker this is called "balancing your ranges". Basically it means making sure that when you do any given externally observable act, you do that same act with multiple different hands, so that the external observable is not highly correlated to a specific hidden state (your hole cards). For example, say you only ever raise under the gun with AA/KK - we would say your "range is not balanced". One way to fix this is to raise some bluff hands as well. Another way to fix it would be to limp your AA/KK (assuming you limp enough other hands to have balance). If you do limp some hands UTG but then you only reraise with AA/KK , you're unbalanced again, so if you are limping AA UTG then you also need to limp-reraise bluff from UTG sometimes to balance your range.

3 comments:

Autodidactic Asphyxiation said...

In bridge, there is a related comment called the "skip bid" warning. Basically, if you make some jump bid, the next player might have to think before they bid. But that means the length of the delay gives information to your opponent's partner. You warn "skip bid" to force the next player to wait 10 seconds before making his bid, to remove that side channel.

cbloom said...

Yeah "timing tells" are very useful in poker too. Obviously Ferguson is famous for always taking a long time for every action to hide the times when he really needs a long time to think. Most people find this too tedious.

I guess there must be issues in Bridge with people blinking information to each other or touching their ears, etc.

It seems like competition bridge would have to be played on computers in separate rooms to be fair, and as you say every bid would be done on an exact timer.

Aaron said...

Or never turn on the fan. That works too if you're a stealthy shitter.

old rants