[tlaplus] Why is TLA_ complaining about this? (

[ns <nedsri1988@xxxxxxxxx>]

If I have a property of the form

    [][A => (p /\  [] (q  =>  r))]_vars                                           (1)

where A is an action and p,q,r are state predicates, I get two complaints:

Level error in applying operator $SquareAct:

The level of argument 1 exceeds the maximum level allowed by the operator.

and

=> has both temporal formula and action as arguments.

If I remove the nested [] then both complaints go away (and TLC is fine with too)

    [][A => (p /\  (q  =>  r))]_vars                                                     (2)

However, even if I replace the A with another state predicate the second complaint still remains. 

Could someone tell me where I'm going wrong. I don't recall seeing any restriction on nesting of temporal operators in the Specifying Systems book but I could have quite easily missed it. Regarding why TLC accepts the second formula (2), I assume its "nice" because its considered a Box-Action formula?

thanks

-- 
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+unsubscribe@xxxxxxxxxxxxxxxx.
To view this discussion on the web visit https://groups.google.com/d/msgid/tlaplus/9448bd47-eee3-452d-bcfd-74d4a5a80595n%40googlegroups.com.