LTS Termination Proof

by T2Cert

Input

Integer Transition System

Initial Location: 3

Transitions: (pre-variables and post-variables)

0	0	1:	0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ − arg2P ≤ 0 ∧ − arg2 ≤ 0 ∧ − arg1P ≤ 0 ∧ 1 − arg1 ≤ 0 ∧ − arg1P + arg1 ≤ 0 ∧ arg1P − arg1 ≤ 0 ∧ − arg2P + arg2 ≤ 0 ∧ arg2P − arg2 ≤ 0 ∧ − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0
1	1	2:	0 ≤ 0 ∧ 0 ≤ 0 ∧ 1 + arg2 − 2⋅x10 ≤ 0 ∧ −1 − arg2 + 2⋅x10 ≤ 0 ∧ − arg2 ≤ 0 ∧ 1 − arg1 + arg2 ≤ 0 ∧ − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − arg2P + arg2P ≤ 0 ∧ arg2P − arg2P ≤ 0 ∧ − arg2 + arg2 ≤ 0 ∧ arg2 − arg2 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0
2	2	1:	0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ 1 + arg2 − 2⋅x13 ≤ 0 ∧ −1 − arg2 + 2⋅x13 ≤ 0 ∧ 1 − arg1 + arg2 ≤ 0 ∧ − arg2 ≤ 0 ∧ arg2 − 2⋅x13 ≤ 0 ∧ −1 − arg2 + 2⋅x13 ≤ 0 ∧ 1 − arg2P + arg2 ≤ 0 ∧ −1 + arg2P − arg2 ≤ 0 ∧ − arg2P + arg2 ≤ 0 ∧ arg2P − arg2 ≤ 0 ∧ − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0
1	3	2:	0 ≤ 0 ∧ 0 ≤ 0 ∧ − arg2 ≤ 0 ∧ arg2 − 2⋅x16 ≤ 0 ∧ − arg2 + 2⋅x16 ≤ 0 ∧ 1 − arg1 + arg2 ≤ 0 ∧ − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0 ∧ − arg2P + arg2P ≤ 0 ∧ arg2P − arg2P ≤ 0 ∧ − arg2 + arg2 ≤ 0 ∧ arg2 − arg2 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0
2	4	1:	0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ − arg2 ≤ 0 ∧ 1 − arg1 + arg2 ≤ 0 ∧ arg2 − 2⋅x19 ≤ 0 ∧ − arg2 + 2⋅x19 ≤ 0 ∧ arg2 − 2⋅x19 ≤ 0 ∧ −1 − arg2 + 2⋅x19 ≤ 0 ∧ 2 − arg2P + arg2 ≤ 0 ∧ −2 + arg2P − arg2 ≤ 0 ∧ − arg2P + arg2 ≤ 0 ∧ arg2P − arg2 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0
3	5	0:	0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ 0 ≤ 0 ∧ − arg1P + arg1 ≤ 0 ∧ arg1P − arg1 ≤ 0 ∧ − arg2P + arg2 ≤ 0 ∧ arg2P − arg2 ≤ 0 ∧ − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0

Proof

1 Invariant Updates

The following invariants are asserted.

0:	TRUE
1:	− arg1P ≤ 0 ∧ − arg1 ≤ 0
2:	− arg1P ≤ 0 ∧ − arg1 ≤ 0 ∧ − arg2 ≤ 0
3:	TRUE

The invariants are proved as follows.

IMPACT Invariant Proof

nodes (location) invariant:

0	(0)	TRUE
1	(1)	− arg1P ≤ 0 ∧ − arg1 ≤ 0
2	(2)	− arg1P ≤ 0 ∧ − arg1 ≤ 0 ∧ − arg2 ≤ 0
3	(3)	TRUE

initial node: 3
cover edges:
transition edges:

0 0 1

1 1 2

1 3 2

2 2 1

2 4 1

3 5 0

2 Switch to Cooperation Termination Proof

We consider the following cutpoint-transitions:

− x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0 ∧ − arg2P + arg2P ≤ 0 ∧ arg2P − arg2P ≤ 0 ∧ − arg2 + arg2 ≤ 0 ∧ arg2 − arg2 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0

and for every transition t, a duplicate t is considered.

3 Transition Removal

We remove transitions 0, 5 using the following ranking functions, which are bounded by −11.

3:	0
0:	0
1:	0
2:	0
3:	−4
0:	−5
1:	−6
2:	−6
1_var_snapshot:	−6
1*:	−6

4 Location Addition

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

1* 9 1: − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0 ∧ − arg2P + arg2P ≤ 0 ∧ arg2P − arg2P ≤ 0 ∧ − arg2 + arg2 ≤ 0 ∧ arg2 − arg2 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0

5 Location Addition

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

1 7 1_var_snapshot: − x19 + x19 ≤ 0 ∧ x19 − x19 ≤ 0 ∧ − x16 + x16 ≤ 0 ∧ x16 − x16 ≤ 0 ∧ − x13 + x13 ≤ 0 ∧ x13 − x13 ≤ 0 ∧ − x10 + x10 ≤ 0 ∧ x10 − x10 ≤ 0 ∧ − arg2P + arg2P ≤ 0 ∧ arg2P − arg2P ≤ 0 ∧ − arg2 + arg2 ≤ 0 ∧ arg2 − arg2 ≤ 0 ∧ − arg1P + arg1P ≤ 0 ∧ arg1P − arg1P ≤ 0 ∧ − arg1 + arg1 ≤ 0 ∧ arg1 − arg1 ≤ 0

6 SCC Decomposition

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

6.1 SCC Subproblem 1/1

Here we consider the SCC { 1, 2, 1_var_snapshot, 1* }.

6.1.1 Transition Removal

We remove transitions 2, 3, 4 using the following ranking functions, which are bounded by 4.

1:	2 + 5⋅arg1 − 5⋅arg2
2:	5⋅arg1 − 5⋅arg2
1_var_snapshot:	1 + 5⋅arg1 − 5⋅arg2
1*:	3 + 5⋅arg1 − 5⋅arg2

6.1.2 Transition Removal

We remove transitions 7, 9, 1 using the following ranking functions, which are bounded by −3.

1:	−1
2:	−3
1_var_snapshot:	−2
1*:	0

6.1.3 Splitting Cut-Point Transitions

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

6.1.3.1 Cut-Point Subproblem 1/1

Here we consider cut-point transition 6.

6.1.3.1.1 Splitting Cut-Point Transitions

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

Tool configuration

T2Cert

version: 1.0