About Enabled semantics

10 views
Skip to first unread message

Huailin

unread,
Jul 9, 2021, 7:42:56 PMJul 9
to tlaplus
Team,

I got a quick question about the semantics of Enabled of TLA+. Thanks for the clarification in advance.

As we know, the Enabled Predication is defined as:

s[Enabled A] = Exist t \Exist St: s[[A]]t. 

For the action A, there exists a state t in the state space St, so that action A could be possible to get a chance(may not get the chance, though) to execute.

Then, my question is:  When/after Enabled(A) is TRUE, when it could become false, or we say, why/when the state "t" will run away....? so that we can not match the s[[A]]t any more.

Can you give an example? t run away for a vacation, and then, after a while, come back...then Enabled(A) becomes TRUE again.

Thanks,

Michael

Hillel Wayne

unread,
Jul 10, 2021, 1:33:25 AMJul 10
to tla...@googlegroups.com

Consider

A == x /\ x' = FALSE
B == ~x /\ x' = TRUE

Then ENABLED A <=> ~(ENABLED B).

H

--
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...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/tlaplus/40e686f9-4176-474f-a7a0-77ef7c57b946n%40googlegroups.com.
Reply all
Reply to author
Forward
0 new messages