Thanks guys !!!
I modified the spec and now not getting error.
Actually I was confused by the error trace which showed red highlight on variable i when in states 3,4,5...etc. which led me to think that the invariant is violated at those steps also. I now feel that this is complete error trace leading to i == 21 which actually violated the invariant, not the steps in between.
<Screen Shot 2019-03-23 at 10.34.11 AM.png>
Modified spec with no error:
---------------------------- MODULE RingCounter ----------------------------
EXTENDS Naturals, TLC, Integers
VARIABLES i
TCTypeOK ==
/\ i> 0
/\ i <= 20
Init == i \in (2..20)
Wrap ==
IF i > 19 THEN i' = 1 ELSE i' = i + 1
FirstHalf ==
/\ i<10
/\ Wrap
Mid ==
/\ i=10
/\ Wrap
SecondHalf ==
/\ i>10
/\ Wrap
Next == FirstHalf \/ SecondHalf \/ Mid \/ Wrap
=============================================================================
On Friday, March 22, 2019 at 8:29:08 PM UTC+5:30, Adi wrote:
Hi All,
I'm a total beginner in TLA+ and I'm excited to learn this.
I began watching the TLA+ video lectures and toying with small specs on my own.
I'm facing a issue with model checking error. IN the below spec I expect no errors for values of i between 1 and 20. But model checker is giving error even when i = 3,4....20 giving out "Invariant TCTypeOK is violated."
Am I missing something obvious ?
Thanks in advance,
Adi
---------------------------- MODULE Counter ----------------------------
EXTENDS Naturals, TLC, Integers
VARIABLES i
TCTypeOK ==
/\ i> 1
/\ i < 20
Init == (i=2)
FirstHalf ==
/\ i<10
/\ i' = i+1
Mid ==
/\ i=10
/\ i' = i+1
SecondHalf ==
/\ i>10
/\ i' = i+1
Next == FirstHalf \/ SecondHalf \/ Mid
=============================================================================
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
.
.
.