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Re: [tlaplus] What is a TLA formula and a Temporal formula?

Hi Stephan,

Thanks for your reply.



在 2018年1月26日星期五 UTC+8下午4:10:07,Stephan Merz写道:
Within temporal formulas, action formulas must be "protected", i.e. occur in the form [][A]_v or dually <><<A>>_v.

In particular, <>(<<A>>_v \/ <<B>>_v) does not obey this restriction: the action formulas appear in the immediate scope of \/. Of course, if it were accepted as a formula, it would be equivalent to <><<A>>_v \/ <><<B>>_v, and the latter is a well-formed formula.


On 26 Jan 2018, at 03:53, 杨永 <steph...@xxxxxxxxx> wrote:

Hi, guys

I am reading the Tla+ Specifying Systems confused by TLA formula. For example, on page 95, the first sentence "...because []<>(<<A>>_v \/ <<B>>_v ) isn't a TLA formula." where <<A >>_v and <<B>>_v are actions, however, []<><<A \/ B>>_v is a TLA formula."

I don't know why. Can somebody explain the reason?

I appreciate,


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