Re: [tlaplus] Specifying Systems- BoundedFIFO error- Figure 4.2

Hello,

TLC cannot handle specifications that involve unbounded quantification or quantification over state variables. In your case, `q' is a state variable and Spec should really be defined as

Spec == \EE q: Inner(q)!Init /\ [][BNext(q)]_<<in,out,q>>

where \EE denotes quantification over a state variable (i.e., a sequence of values). Such specifications are not handled by any of the existing verification tools for TLA+.

Regards,

Stephan

On 1 Sep 2022, at 06:27, Anand Kumar <akkeshavan@xxxxxxxxx> wrote:

Hi,

"The configuration file did not specify the initial state predicate.
Can also be caused by trying to run TLC on a specification from
a module imported with a parameterized INSTANCE statement."

This is my spec, what am I doing wrong? Similar error comes in the FIFO spec lso. I have checked your earlier answer, but that doesn;t seem to provide a solution. I understand the Professor Lamport prefers us to use the Hyperbook, but that gives a lot fo permission errors etc on a mac.

Sorry to trouble you with this-- but since i am new to this I would really appreciate the help.
EXTENDS Naturals, Sequences
CONSTANT Message,N
VARIABLES in, out

ASSUME (N \in Nat) /\ (N > 0 )

Inner(q) == INSTANCE InnerFIFO

BNext(q) ==
/\ Inner(q)! Next
/\ Inner(q)! BufReceive => (Len(q) < N )

Spec == \E q: Inner(q)!Init /\ [][BNext(q)]_<<in,out,q>>

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