In the Editor sidebar, look under the collapsible panel called Node properties. When you select a decision node in the game tree, this panel will let you change the decision node’s properties.
A decision can have one or more choices. A decision must have at least one possible choice, so it is not possible to remove the last choice. Choose which player should be making this decision from the “Player” dropdown.
The way a decision node works is that the player who gets to make the decision picks one of the choices. The player picks using a strategy which depends on private information. For each private item in the player’s range, the player’s strategy can allocate the decision between the choices. For example, if the player’s private information is that the player is either weak or strong, and the choices are “be aggressive” or “fall back,” the player’s strategy when strong might be to be aggressive 100% of the time, and the player’s strategy when weak might be to be aggressive 20% of the time and to fall back 80% of the time.
By default, GameTreeCalculator will calculate the optimal strategy for every decision node. If you move the slider to “Fixed strategy,” a grid will appear where you can manually enter a strategy. If you choose a fixed strategy, the calculator will not attempt to calculate the optimal strategy — it will simply apply the fixed strategy you entered. The values in every row of the fixed strategy table should sum to 1. If they do not scale to 1, they will be scaled so that they do. This can be useful if you want to enter relative weights. For example, if you enter “2” and “3,” the weights will be automatically scaled to 0.4 (40%) and 0.6 (60%) when you save.
You will probably generally want to leave the “Infoset” blank. If you enter a value here, and you enter the same value on other decision nodes, they will be part of the same infoset. This means that when the calculator is calculating an optimal strategy for any node within the infoset, it will group those nodes together so that it only knows that it is inside the infoset, not which node in the infoset is the current node. The result is that the optimal strategy will not depend on which infoset node is the current node.
Remember to press the Save button any time you make changes to this panel. Otherwise, your changes will not be applied to the game tree.