[rules-users] Rule evaluation logic

[MarcoMojana]

I have reduced my problem to a minimal example:
   - I use a pseudo clock and stream mode processing
   - The events are inserted using a succession of advanceTime(), insert(),
fireAllRules()
   - I have three events named: Thief, SwitchOn and SwitchOff
   - I have three rules similar to:
rule "detect theft"
	when
		$t : Thief() from entry-point "thieves"		// Line A
		$lastSwitchOn : SwitchOn(this before $t) from entry-point "lightsControl"
// Line B
		SwitchOff(this before $t, this after $lastSwitchOn) from entry-point
"lightsControl"	// Line C
		not( SwitchOff(this before $t, this after $lastSwitchOn) from entry-point
"lightsControl" )	// Line D
	then
		System.out.println($t);
end

     The first rule is composed of lines A, B, the second of lines A, B and
C and the third of lines A, B and D. Please note that line D is the negation
of line C.

   - Inserting the same sequence of events, only the first rule triggers.
This seems strange to me, because:
   1) if the first rule triggers, then "Line A" and "Line B" = true
   2) if the second rule doesn't, then "Line A" and "Line B" and "Line C" =
false. 
   3) from 1) and 2), it follows "Line C" = false
   4) from 1) and 3), it follows that "Line A" and "Line B" and not "Line C"
= true, so the third rule should be triggered, but it is not. Why?

-- 
MM


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