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LINEAR TEMPORAL LOGIC. Fall 2013 Dr. Eric Rozier. Propositional Temporal Logic. Does the following hold?. yes. Propositional Temporal Logic. Does the following hold?. no. G F p p holds infinitely often F G p Eventually, p holds henceforth G ( p => F q )
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LINEAR TEMPORAL LOGIC Fall 2013 Dr. Eric Rozier
Propositional Temporal Logic Does the following hold? yes
Propositional Temporal Logic Does the following hold? no
G Fp p holds infinitely often F Gp Eventually, p holds henceforth G( p=> Fq ) Every p is eventually followed by a q F( p => (X Xq) ) Every p is followed by a q two reactions later Examples: What do they mean? Remember: Gp p holds in all states Fp p holds eventually Xp p holds in the next state
“Whenever the iRobot is at the ramp-edge (cliff), eventually it moves 5 cm away from the cliff.” p – iRobot is at the cliff q – iRobot is 5 cm away from the cliff G (p => F q) “Whenever the distance between cars is less than 2m, cruise control is deactivated” p – distance between cars is less than 2 m q – cruise control is active G (p => X ! q) Examples: Write in Temporal Logic
Remember, LTL Formulas are Formulas • Suppose the robot must visit a set of n locations l1, l2, …, ln. Let pi be an atomic formula that is true if and only if the robot visits location li. • Express the following: • The robot must eventually visit at least one of the n locations.
Remember, LTL Formulas are Formulas • Suppose the robot must visit a set of n locations l1, l2, …, ln. Let pi be an atomic formula that is true if and only if the robot visits location li. • Express the following: • The robot must eventually visit all n locations, but in any order.
Remember, LTL Formulas are Formulas • Suppose the robot must visit a set of n locations l1, l2, …, ln. Let pi be an atomic formula that is true if and only if the robot visits location li. • Express the following: • The robot must eventually visit all n locations, in numeric order.
What does this property mean? • F(p => Xq) • Is it satisfied by this trace? p -> p -> p -> __ -> q -> p -> …
What does this property mean? • F(p => Xq) • Is it satisfied by this trace? p -> p -> p -> __ -> q -> p -> q -> …
Does this automaton satisfy the property? • F(p & XXX !q)
Does this automaton satisfy the property? • F(p & XXX !q)
Does this automaton satisfy the property? • F(p & XXX !q)