Hi Amirhosein
,
I am also new to the Google group mailing list but I can describe my approach to learning TLA+:
1. I started with the book [1]
2. then I have moved to GitHub sources [2]
3. What I have found very useful is all the content from Hille Wayne [3]
and then when I grasped the first beginner phase of learning TLA+ I tried to experiment with the Chat-GPT 4 and generate such examples as you mentioned and I was impressed with the results.
A straightforward example of a recursive function model in TLA+
```
----------------- MODULE Factorial -----------------
EXTENDS Naturals
VARIABLES n, result
(* Recursive factorial function *)
RECURSIVE Fact(_)
Fact(x) ==
IF x = 0 THEN 1
ELSE x * Fact(x-1)
(* Initialization *)
Init ==
/\ n \in 0..5 (* We limit n to a small number for illustration purposes *)
/\ result = Fact(n)
(* Safety property: The result should be the factorial of n *)
Safety == result = Fact(n)
====================================================
```
Spec could be defined as Spec == Init /\ [][UNCHANGED <<n, result>>]_<<n, result>>
Best regards,
Ing. Maros Orsak,
Senior Software Quality Enginner