You used the word Boolean, you got PLEG.
Here's a super short pleg breakdown.
Inputs are the data that gets used in the logic. There are 5 flavors: triggers (true/false), schedules (t/f) and device properties (numeric or string), counters (ordinal/time) and house modes (home/away/etc). Here is a way to tell when to use a trigger vs property : trigger on temp >85 =True vs property temp =92.
Inputs have a value and timestamps of when they became true/false or updated. So that find when the temp went above 85, use the #trigger. To find out the last time it was below 85 use !#trigger. To know when the temp was last updated you would use #property.
Conditions are complex true/false and have the Boolean logic. So if you want the AC to come on at 85, you would just need a "trigger". If you want a condition to turn off the access after it drops below 85, use "!trigger"
If you want an alert if the temp has been above 85 for more than an hour the condition would be "trigger and (trigger; Now >60:00)"
Conditions can be used to start scenes. This let's you do AND/OR when the UI doesn't.