A formula is a set of requirements that must be met before someone can challenge you to a game or accept your offer for a game in the seekgraph.
To set your formula go to the Toolbar above in Dasher. Click on the Settings icon and choose the Formula tab. (Or: Menu above: Edit > Settings > Formula Tab)
You may view your current formula with the command '/vars' or Menu above in Dasher: Edit > Settings > Formula Tab.
If you want your formula to be used to screen people who accept your seek ad, you must type '/set useformula on' before you issue the seek. You only have to type this once. It is saved.
Formulae do not apply to "rematch" challenges, and the pools like 1-minute, 5-minute, etc.