A simple preflop tree

Let's start off with a basic tree: Click here for download.
To open the savefile, start CardRunnersEV, go to File->Open... in the menu and select the savefile.

The tree

Here we see a basic SB versus BB decision tree.
Small blind raises pot with 50% of his range, big blind 3-bets with some hands and folds the others, small blind 4-bets or folds, big blind pushes or folds, leaving small bind to act.

Mouse over a range to see what's in it

To quickly see the ranges that are used, move your mouse over the name of the string to get a small matrix.
To edit the range, you can now double-click, but we'll get into that a bit later.

The composition of decision trees: Decision nodes, actions and conditions

A decision tree is made up out of several components.
At each point in time a player will have a decision to make.
At such a point in time, a player can decide to take several actions.
Examples of such actions would be to "Raise to 9" or to "Fold".
Whether a player takes one action or another is decided by the conditions under which an action is taken.
For example, holding AA would be a good condition for a player to decide to raise.

In the software, the decision points for a player are symbolized with white oval decision nodes.
A decision node will lead to several possible actions. For example, in the screenshot above, BB is deciding between Raise to 9 and Fold.

Beneath each action is a list of the conditions under which the action is taken.
In our simple tree only one condition is given for each action.
However, it is also possible for there to be multiple conditions.

If multiple conditions are present, they will be treated as OR.
So the action will be performed if ány of the conditions are TRUE.

The data beneath the nodes

Beneath each decision node, in blue, is some data that gives information regarding the situation at thát point in the hand:
- Pot: The size of the pot, meaning all the money that has been bet so far
- To call: The amount the player needs to call to match the current bet
- Odds: The odds that the player is getting
- Stack: The amount of money that the player still has left

End points

After the small blind's last decision we can see that the tree ends in either a green arrow or a blue line.
Those are the end points of a tree.
They occur if there's no one left to act.

The green arrow occurs when the remaining players go to showdown.
The blue line occurs if everyone except one player has folded.