Re: [tlaplus] AND operator

[Diep Chi Pham]

Hi,

I think:  IF  x = .. /\ y = ..  THEN ...

Cheers,

DC

On Wed, Feb 10, 2021 at 9:31 PM Anshu ranjan <a.ranj...@gmail.com> wrote:

Hi, I have a beginner's question:
If I want to write the following clause:

IF x=true and y=true

THEN do z

How can write this in TLA+? Specifically how do I write the and operator?

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[Anshu ranjan]

Yeah I it was indeed just /\. 
What I was missing is an else statement.. So I added:  else TRUE, and it worked fine.

[Freeman, Steve]

If you use a font like FiraCode with ligatures for technical symbols like this, the code becomes more readable.

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[Martin]

Hello,

Just a remark if you are designing your Next state relation: this is often
written as a disjunction of actions (which makes non-determinism possible). What
you might want to write could be along the lines of:

\/ (x /\ y /\ z' = 42)
\/ (x /\ ~y /\ z' = 11)
\/ (~x /\ z' = 23)

This amounts to stating "if x and y hold, then the next value of z is 42, if x
but not y holds, then the next value of z is 11; if x does not hold then the
next value of z is 23". In this example all cases are mutually exclusive but
that's not necessary (e.g. just remove the /\ y from the first line).

hope this helps! kind regards,
Martin

On 2/10/21 9:31 PM, Anshu ranjan wrote:
> Hi, I have a beginner's question:
> If I want to write the following clause:
>
> IF x=true and y=true
> THEN do z
>
> How can write this in TLA+? Specifically how do I write the and operator?
>
> --
> 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

> <mailto:tlaplus+u...@googlegroups.com>.

> To view this discussion on the web visit
> https://groups.google.com/d/msgid/tlaplus/407236e0-4a88-4ced-b3f2-629a252ddba9n%40googlegroups.com

> <https://groups.google.com/d/msgid/tlaplus/407236e0-4a88-4ced-b3f2-629a252ddba9n%40googlegroups.com?utm_medium=email&utm_source=footer>.

[Anshu ranjan]

Thank you all for the help. I ended up using IF .. THEN .. ELSE TRUE, which seemed easiest.