LTS Termination Proof

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Input

Integer Transition System

Proof

1 Switch to Cooperation Termination Proof

We consider the following cutpoint-transitions:
1 3 1: arg2P + arg2P ≤ 0arg2Parg2P ≤ 0arg2 + arg2 ≤ 0arg2arg2 ≤ 0arg1P + arg1P ≤ 0arg1Parg1P ≤ 0arg1 + arg1 ≤ 0arg1arg1 ≤ 0
and for every transition t, a duplicate t is considered.

2 Transition Removal

We remove transitions 0, 2 using the following ranking functions, which are bounded by −11.

2: 0
0: 0
1: 0
2: −4
0: −5
1: −6
1_var_snapshot: −6
1*: −6

3 Location Addition

The following skip-transition is inserted and corresponding redirections w.r.t. the old location are performed.

1* 6 1: arg2P + arg2P ≤ 0arg2Parg2P ≤ 0arg2 + arg2 ≤ 0arg2arg2 ≤ 0arg1P + arg1P ≤ 0arg1Parg1P ≤ 0arg1 + arg1 ≤ 0arg1arg1 ≤ 0

4 Location Addition

The following skip-transition is inserted and corresponding redirections w.r.t. the old location are performed.

1 4 1_var_snapshot: arg2P + arg2P ≤ 0arg2Parg2P ≤ 0arg2 + arg2 ≤ 0arg2arg2 ≤ 0arg1P + arg1P ≤ 0arg1Parg1P ≤ 0arg1 + arg1 ≤ 0arg1arg1 ≤ 0

5 SCC Decomposition

We consider subproblems for each of the 1 SCC(s) of the program graph.

5.1 SCC Subproblem 1/1

Here we consider the SCC { 1, 1_var_snapshot, 1* }.

5.1.1 Splitting Cut-Point Transitions

We consider 1 subproblems corresponding to sets of cut-point transitions as follows.

5.1.1.1 Cut-Point Subproblem 1/1

Here we consider cut-point transition 3.

5.1.1.1.1 Fresh Variable Addition

The new variable __snapshot_1_arg2P is introduced. The transition formulas are extended as follows:

4: __snapshot_1_arg2Parg2Parg2P__snapshot_1_arg2P
6: __snapshot_1_arg2P__snapshot_1_arg2P__snapshot_1_arg2P__snapshot_1_arg2P
1: __snapshot_1_arg2P__snapshot_1_arg2P__snapshot_1_arg2P__snapshot_1_arg2P

5.1.1.1.2 Fresh Variable Addition

The new variable __snapshot_1_arg2 is introduced. The transition formulas are extended as follows:

4: __snapshot_1_arg2arg2arg2__snapshot_1_arg2
6: __snapshot_1_arg2__snapshot_1_arg2__snapshot_1_arg2__snapshot_1_arg2
1: __snapshot_1_arg2__snapshot_1_arg2__snapshot_1_arg2__snapshot_1_arg2

5.1.1.1.3 Fresh Variable Addition

The new variable __snapshot_1_arg1P is introduced. The transition formulas are extended as follows:

4: __snapshot_1_arg1Parg1Parg1P__snapshot_1_arg1P
6: __snapshot_1_arg1P__snapshot_1_arg1P__snapshot_1_arg1P__snapshot_1_arg1P
1: __snapshot_1_arg1P__snapshot_1_arg1P__snapshot_1_arg1P__snapshot_1_arg1P

5.1.1.1.4 Fresh Variable Addition

The new variable __snapshot_1_arg1 is introduced. The transition formulas are extended as follows:

4: __snapshot_1_arg1arg1arg1__snapshot_1_arg1
6: __snapshot_1_arg1__snapshot_1_arg1__snapshot_1_arg1__snapshot_1_arg1
1: __snapshot_1_arg1__snapshot_1_arg1__snapshot_1_arg1__snapshot_1_arg1

5.1.1.1.5 Invariant Updates

The following invariants are asserted.

0: TRUE
1: arg1arg1P + arg2arg2P ≤ 0arg1Parg2P ≤ 0arg2 ≤ 0arg1arg1P + arg2arg2P ≤ 0−1 − arg1P + arg2arg2P ≤ 0
2: TRUE
1: arg1arg1P + arg2arg2P ≤ 0arg1Parg2P ≤ 0arg2 ≤ 0arg1arg1P + arg2arg2P ≤ 0−1 − arg1P + arg2arg2P ≤ 01 − __snapshot_1_arg1P__snapshot_1_arg2P + arg1P + arg2P ≤ 0__snapshot_1_arg1P__snapshot_1_arg2P ≤ 0arg1arg1P + arg2arg2P ≤ 0−1 − arg1P + arg2arg2P ≤ 0
1_var_snapshot: __snapshot_1_arg1P__snapshot_1_arg2P + arg1 + arg2 ≤ 0__snapshot_1_arg1P__snapshot_1_arg2P ≤ 0arg2 ≤ 0__snapshot_1_arg1P__snapshot_1_arg2P + arg1 + arg2 ≤ 0−1 − __snapshot_1_arg1P__snapshot_1_arg2P + arg2 ≤ 0
1*: arg1arg1P + arg2arg2P ≤ 0−1 − arg1P + arg2arg2P ≤ 01 − __snapshot_1_arg1P__snapshot_1_arg2P + arg1P + arg2P ≤ 0__snapshot_1_arg1P__snapshot_1_arg2P ≤ 0

The invariants are proved as follows.

IMPACT Invariant Proof

5.1.1.1.6 Transition Removal

We remove transition 6 using the following ranking functions, which are bounded by −2.

1: arg1P + arg2P
1_var_snapshot: __snapshot_1_arg1P + __snapshot_1_arg2P
1*: __snapshot_1_arg1P + __snapshot_1_arg2P

5.1.1.1.7 Transition Removal

We remove transition 4 using the following ranking functions, which are bounded by −5.

1: −1
1_var_snapshot: −2
1*: −3

5.1.1.1.8 Splitting Cut-Point Transitions

There remain no cut-point transition to consider. Hence the cooperation termination is trivial.

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