Dear Petar,
welcome to this group.
In order to answer your question: the SMT backend of the proof system is not able to prove temporal logic formulas. You should decompose your proof as follows: THEOREM Spec => []Invariant <1>1. Init => Invariant <1>2. Invariant /\ [Next]_<<CarsGo, PedestriansGo>> => Invariant' <1>. QED BY <1>1, <1>2, PTL DEF Spec
The nontemporal steps <1>1 and <1>2 should be provable using SMT, but the PTL backend has to be used for the final step. You may also want to read the tutorial on the TLAPS Web site.

However, I am not sure if it is a good idea to introduce the proof system for your presentation. I would imagine that you are better off showing the model checker, all the more for a finitestate specification such as yours.
Best regards, Stephan Dear all TLA lovers,I am very new to TLA, but I read the Amazon article and I was very much intrigued by this tool so I wanted to learn more.In one of my masters courses we learning about modelling specifications and trying to generate test cases from them or proof some of our assumptions about specifications.I talked to my professor about TLA+ and she liked it as well, so she told me to prepare a short introduction to it on Special Topics class. My task is to create a simple model of a sempaphore in TLA+.To this end, I created the following TLA+ specification: MODULE semaphore VARIABLES CarsGo, PedestriansGo\* Initial stateInit == \/ /\ CarsGo = TRUE /\ PedestriansGo = FALSE \/ /\ CarsGo = FALSE /\ PedestriansGo = TRUE\* Next stepNext == /\ CarsGo' = ~CarsGo /\ PedestriansGo' = ~PedestriansGoSpec == Init /\ [][Next]_<<CarsGo, PedestriansGo>>Invariant == CarsGo # PedestriansGoTHEOREM Spec => []Invariant BY DEF Spec, Invariant============================================================================However, when I try to prove the theorem, I get the message:(* SMT failed with status = sat *).Can someone explain me what I am doing wrong?Kindest regards,Thanks in advance,Petar Vukmirovic. You received this message because you are subscribed to the Google Groups "tlaplus" group.To unsubscribe from this group and stop receiving emails from it, send an email to tlaplus+u...@xxxxxxxxxxxxxxxx.To post to this group, send email to tla...@xxxxxxxxxxxxxxxx.Visit this group at https://groups.google.com/group/tlaplus.For more options, visit https://groups.google.com/d/optout.
