libtlafmt 0.4.1

A formatter library for TLA+ specs, core of tlafmt
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66

---
source: libtlafmt/tests/format.rs
expression: output
input_file: libtlafmt/tests/corpus/SyncTerminationDetection.tla
---
----------------------- MODULE SyncTerminationDetection ------------------------
(***************************************************************************)
(* An abstract specification of the termination detection problem in a     *)
(* ring with synchronous communication.                                    *)
(***************************************************************************)
EXTENDS Naturals
CONSTANT N
ASSUME NAssumption == N \in Nat \ {0}

Node == 0..N - 1

VARIABLES
    active,             \* activation status of nodes
    terminationDetected \* has termination been detected?

TypeOK ==
    /\ active \in [Node -> BOOLEAN ]
    /\ terminationDetected \in BOOLEAN

terminated == \A n \in Node: ~active[n]

(***************************************************************************)
(* Initial condition: the nodes can be active or inactive, termination     *)
(* may (but need not) be detected immediately if all nodes are inactive.   *)
(***************************************************************************)
Init ==
    /\ active \in [Node -> BOOLEAN ]
    /\ terminationDetected \in {FALSE, terminated}

Terminate(i) == \* node i terminates
    /\ active[i]
    /\ active' = [active EXCEPT ![i] = FALSE]
    (* possibly (but not necessarily) detect termination if all nodes are inactive *)
    /\ terminationDetected' \in {terminationDetected, terminated'}

Wakeup(i, j) == \* node i activates node j
    /\ active[i]
    /\ active' = [active EXCEPT ![j] = TRUE]
    /\ UNCHANGED terminationDetected

DetectTermination ==
    /\ terminated
    /\ terminationDetected' = TRUE
    /\ UNCHANGED active

Next ==
    \/ \E i \in Node: Terminate(i)
    \/ \E i, j \in Node: Wakeup(i, j)
    \/ DetectTermination

vars == << active, terminationDetected >>
Spec == Init /\ [][Next]_vars /\ WF_vars(DetectTermination)

Stable == [](terminationDetected => []terminated)

Live == terminated ~> terminationDetected

================================================================================
\* Modification History
\* Last modified Thu Jan 21 16:08:09 CET 2021 by merz
\* Created Sun Jan 10 15:19:20 CET 2021 by merz