Execution Chart

We display below the execution chart for this examination (boot time has been removed).

Trace from the execution

Formatting '/data/fkordon/mcc2024-input.r496-tall-171640603800607.qcow2', fmt=qcow2 size=4294967296 backing_file=/data/fkordon/mcc2024-input.qcow2 backing_fmt=qcow2 cluster_size=65536 lazy_refcounts=off refcount_bits=16
Waiting for the VM to be ready (probing ssh)
.................
=====================================================================
Generated by BenchKit 2-5568
Executing tool ltsminxred
Input is GPUForwardProgress-PT-36b, examination is ReachabilityFireability
Time confinement is 3600 seconds
Memory confinement is 16384 MBytes
Number of cores is 4
Run identifier is r496-tall-171640603800607
=====================================================================

--------------------
preparation of the directory to be used:
/home/mcc/execution
total 544K
-rw-r--r-- 1 mcc users 6.8K May 14 13:22 CTLCardinality.txt
-rw-r--r-- 1 mcc users 71K May 14 13:22 CTLCardinality.xml
-rw-r--r-- 1 mcc users 5.7K May 14 13:22 CTLFireability.txt
-rw-r--r-- 1 mcc users 53K May 14 13:22 CTLFireability.xml
-rw-r--r-- 1 mcc users 3.8K Apr 22 14:47 LTLCardinality.txt
-rw-r--r-- 1 mcc users 27K Apr 22 14:47 LTLCardinality.xml
-rw-r--r-- 1 mcc users 2.3K Apr 22 14:47 LTLFireability.txt
-rw-r--r-- 1 mcc users 18K Apr 22 14:47 LTLFireability.xml
-rw-r--r-- 1 mcc users 6.9K Apr 11 22:27 ReachabilityCardinality.txt
-rw-r--r-- 1 mcc users 61K Apr 11 22:27 ReachabilityCardinality.xml
-rw-r--r-- 1 mcc users 7.5K Apr 11 22:27 ReachabilityFireability.txt
-rw-r--r-- 1 mcc users 63K Apr 11 22:27 ReachabilityFireability.xml
-rw-r--r-- 1 mcc users 1.8K Apr 22 14:47 UpperBounds.txt
-rw-r--r-- 1 mcc users 3.8K Apr 22 14:47 UpperBounds.xml
-rw-r--r-- 1 mcc users 6 May 18 16:42 equiv_col
-rw-r--r-- 1 mcc users 4 May 18 16:42 instance
-rw-r--r-- 1 mcc users 6 May 18 16:42 iscolored
-rw-r--r-- 1 mcc users 179K May 18 16:42 model.pnml

--------------------
content from stdout:

=== Data for post analysis generated by BenchKit (invocation template)

The expected result is a vector of booleans
BOOL_VECTOR

here is the order used to build the result vector(from text file)
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-00
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-01
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-02
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-03
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-04
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-05
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-06
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-07
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-08
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-09
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-10
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-11
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-12
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-13
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-14
FORMULA_NAME GPUForwardProgress-PT-36b-ReachabilityFireability-2024-15

=== Now, execution of the tool begins

BK_START 1717199131143

Invoking MCC driver with
BK_TOOL=ltsminxred
BK_EXAMINATION=ReachabilityFireability
BK_BIN_PATH=/home/mcc/BenchKit/bin/
BK_TIME_CONFINEMENT=3600
BK_INPUT=GPUForwardProgress-PT-36b
BK_MEMORY_CONFINEMENT=16384
Applying reductions before tool ltsmin
Invoking reducer
Running Version 202405141337
[2024-05-31 23:45:32] [INFO ] Running its-tools with arguments : [-pnfolder, /home/mcc/execution, -examination, ReachabilityFireability, -timeout, 360, -rebuildPNML]
[2024-05-31 23:45:32] [INFO ] Parsing pnml file : /home/mcc/execution/model.pnml
[2024-05-31 23:45:32] [INFO ] Load time of PNML (sax parser for PT used): 97 ms
[2024-05-31 23:45:32] [INFO ] Transformed 720 places.
[2024-05-31 23:45:32] [INFO ] Transformed 757 transitions.
[2024-05-31 23:45:32] [INFO ] Found NUPN structural information;
[2024-05-31 23:45:32] [INFO ] Parsed PT model containing 720 places and 757 transitions and 1877 arcs in 202 ms.
Parsed 16 properties from file /home/mcc/execution/ReachabilityFireability.xml in 21 ms.
Working with output stream class java.io.PrintStream
RANDOM walk for 40000 steps (131 resets) in 1811 ms. (22 steps per ms) remains 10/16 properties
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-12 TRUE TECHNIQUES TOPOLOGICAL RANDOM_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-11 FALSE TECHNIQUES TOPOLOGICAL RANDOM_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-10 TRUE TECHNIQUES TOPOLOGICAL RANDOM_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-04 TRUE TECHNIQUES TOPOLOGICAL RANDOM_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-02 TRUE TECHNIQUES TOPOLOGICAL RANDOM_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-01 TRUE TECHNIQUES TOPOLOGICAL RANDOM_WALK
BEST_FIRST walk for 40004 steps (12 resets) in 222 ms. (179 steps per ms) remains 10/10 properties
BEST_FIRST walk for 40003 steps (12 resets) in 770 ms. (51 steps per ms) remains 10/10 properties
BEST_FIRST walk for 40004 steps (12 resets) in 121 ms. (327 steps per ms) remains 9/10 properties
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-05 TRUE TECHNIQUES TOPOLOGICAL BESTFIRST_WALK
BEST_FIRST walk for 40004 steps (12 resets) in 167 ms. (238 steps per ms) remains 9/9 properties
BEST_FIRST walk for 40004 steps (13 resets) in 112 ms. (354 steps per ms) remains 9/9 properties
BEST_FIRST walk for 40004 steps (12 resets) in 77 ms. (512 steps per ms) remains 9/9 properties
BEST_FIRST walk for 40003 steps (10 resets) in 148 ms. (268 steps per ms) remains 9/9 properties
BEST_FIRST walk for 40002 steps (9 resets) in 116 ms. (341 steps per ms) remains 9/9 properties
BEST_FIRST walk for 40004 steps (12 resets) in 121 ms. (327 steps per ms) remains 9/9 properties
BEST_FIRST walk for 40004 steps (13 resets) in 101 ms. (392 steps per ms) remains 9/9 properties
// Phase 1: matrix 757 rows 720 cols
[2024-05-31 23:45:33] [INFO ] Computed 38 invariants in 25 ms
All remaining problems are real, not stopping.
At refinement iteration 0 (INCLUDED_ONLY) 0/160 variables, 160/160 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 1 (INCLUDED_ONLY) 0/160 variables, 0/160 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 2 (OVERLAPS) 558/718 variables, 37/197 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 3 (INCLUDED_ONLY) 0/718 variables, 558/755 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 4 (INCLUDED_ONLY) 0/718 variables, 0/755 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 5 (OVERLAPS) 1/719 variables, 1/756 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 6 (INCLUDED_ONLY) 0/719 variables, 1/757 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 7 (INCLUDED_ONLY) 0/719 variables, 0/757 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 8 (OVERLAPS) 757/1476 variables, 719/1476 constraints. Problems are: Problem set: 0 solved, 9 unsolved
At refinement iteration 9 (INCLUDED_ONLY) 0/1476 variables, 0/1476 constraints. Problems are: Problem set: 0 solved, 9 unsolved
Problem GPUForwardProgress-PT-36b-ReachabilityFireability-2024-13 is UNSAT
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-13 FALSE TECHNIQUES SMT_REFINEMENT
At refinement iteration 10 (OVERLAPS) 1/1477 variables, 1/1477 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 11 (INCLUDED_ONLY) 0/1477 variables, 1/1478 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 12 (INCLUDED_ONLY) 0/1477 variables, 0/1478 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 13 (OVERLAPS) 0/1477 variables, 0/1478 constraints. Problems are: Problem set: 1 solved, 8 unsolved
No progress, stopping.
After SMT solving in domain Real declared 1477/1477 variables, and 1478 constraints, problems are : Problem set: 1 solved, 8 unsolved in 1851 ms.
Refiners :[Domain max(s): 720/720 constraints, Generalized P Invariants (flows): 38/38 constraints, State Equation: 720/720 constraints, PredecessorRefiner: 9/9 constraints, Known Traps: 0/0 constraints]
Escalating to Integer solving :Problem set: 1 solved, 8 unsolved
At refinement iteration 0 (INCLUDED_ONLY) 0/141 variables, 141/141 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 1 (INCLUDED_ONLY) 0/141 variables, 0/141 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 2 (OVERLAPS) 577/718 variables, 37/178 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 3 (INCLUDED_ONLY) 0/718 variables, 577/755 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 4 (INCLUDED_ONLY) 0/718 variables, 0/755 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 5 (OVERLAPS) 1/719 variables, 1/756 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 6 (INCLUDED_ONLY) 0/719 variables, 1/757 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 7 (INCLUDED_ONLY) 0/719 variables, 0/757 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 8 (OVERLAPS) 757/1476 variables, 719/1476 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 9 (INCLUDED_ONLY) 0/1476 variables, 8/1484 constraints. Problems are: Problem set: 1 solved, 8 unsolved
At refinement iteration 10 (INCLUDED_ONLY) 0/1476 variables, 0/1484 constraints. Problems are: Problem set: 1 solved, 8 unsolved
Problem GPUForwardProgress-PT-36b-ReachabilityFireability-2024-07 is UNSAT
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-07 TRUE TECHNIQUES SMT_REFINEMENT
Problem GPUForwardProgress-PT-36b-ReachabilityFireability-2024-14 is UNSAT
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-14 TRUE TECHNIQUES SMT_REFINEMENT
At refinement iteration 11 (OVERLAPS) 1/1477 variables, 1/1485 constraints. Problems are: Problem set: 3 solved, 6 unsolved
At refinement iteration 12 (INCLUDED_ONLY) 0/1477 variables, 1/1486 constraints. Problems are: Problem set: 3 solved, 6 unsolved
At refinement iteration 13 (INCLUDED_ONLY) 0/1477 variables, 0/1486 constraints. Problems are: Problem set: 3 solved, 6 unsolved
At refinement iteration 14 (OVERLAPS) 0/1477 variables, 0/1486 constraints. Problems are: Problem set: 3 solved, 6 unsolved
No progress, stopping.
After SMT solving in domain Int declared 1477/1477 variables, and 1486 constraints, problems are : Problem set: 3 solved, 6 unsolved in 5013 ms.
Refiners :[Domain max(s): 720/720 constraints, Generalized P Invariants (flows): 38/38 constraints, State Equation: 720/720 constraints, PredecessorRefiner: 8/9 constraints, Known Traps: 0/0 constraints]
After SMT, in 7024ms problems are : Problem set: 3 solved, 6 unsolved
Fused 6 Parikh solutions to 2 different solutions.
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-09 FALSE TECHNIQUES PARIKH_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-08 TRUE TECHNIQUES PARIKH_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-06 TRUE TECHNIQUES PARIKH_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-03 FALSE TECHNIQUES PARIKH_WALK
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-00 TRUE TECHNIQUES PARIKH_WALK
Parikh walk visited 5 properties in 249 ms.
Support contains 8 out of 720 places. Attempting structural reductions.
Starting structural reductions in REACHABILITY mode, iteration 0 : 720/720 places, 757/757 transitions.
Graph (trivial) has 629 edges and 720 vertex of which 7 / 720 are part of one of the 1 SCC in 4 ms
Free SCC test removed 6 places
Drop transitions (Empty/Sink Transition effects.) removed 9 transitions
Reduce isomorphic transitions removed 9 transitions.
Graph (complete) has 1084 edges and 714 vertex of which 673 are kept as prefixes of interest. Removing 41 places using SCC suffix rule.2 ms
Discarding 41 places :
Also discarding 2 output transitions
Drop transitions (Output transitions of discarded places.) removed 2 transitions
Drop transitions (Empty/Sink Transition effects.) removed 1 transitions
Reduce isomorphic transitions removed 1 transitions.
Drop transitions (Trivial Post-Agglo cleanup.) removed 396 transitions
Trivial Post-agglo rules discarded 396 transitions
Performed 396 trivial Post agglomeration. Transition count delta: 396
Iterating post reduction 0 with 397 rules applied. Total rules applied 399 place count 673 transition count 349
Reduce places removed 396 places and 0 transitions.
Ensure Unique test removed 34 transitions
Reduce isomorphic transitions removed 34 transitions.
Performed 1 Post agglomeration using F-continuation condition.Transition count delta: 1
Iterating post reduction 1 with 431 rules applied. Total rules applied 830 place count 277 transition count 314
Reduce places removed 1 places and 0 transitions.
Iterating post reduction 2 with 1 rules applied. Total rules applied 831 place count 276 transition count 314
Performed 77 Pre agglomeration using Quasi-Persistent + Divergent Free condition..
Pre-agglomeration after 3 with 77 Pre rules applied. Total rules applied 831 place count 276 transition count 237
Deduced a syphon composed of 77 places in 1 ms
Reduce places removed 77 places and 0 transitions.
Iterating global reduction 3 with 154 rules applied. Total rules applied 985 place count 199 transition count 237
Discarding 40 places :
Symmetric choice reduction at 3 with 40 rule applications. Total rules 1025 place count 159 transition count 197
Iterating global reduction 3 with 40 rules applied. Total rules applied 1065 place count 159 transition count 197
Ensure Unique test removed 1 transitions
Reduce isomorphic transitions removed 1 transitions.
Iterating post reduction 3 with 1 rules applied. Total rules applied 1066 place count 159 transition count 196
Performed 104 Post agglomeration using F-continuation condition.Transition count delta: 104
Deduced a syphon composed of 104 places in 1 ms
Reduce places removed 104 places and 0 transitions.
Iterating global reduction 4 with 208 rules applied. Total rules applied 1274 place count 55 transition count 92
Discarding 31 places :
Symmetric choice reduction at 4 with 31 rule applications. Total rules 1305 place count 24 transition count 30
Iterating global reduction 4 with 31 rules applied. Total rules applied 1336 place count 24 transition count 30
Performed 2 Post agglomeration using F-continuation condition.Transition count delta: 0
Deduced a syphon composed of 2 places in 0 ms
Reduce places removed 2 places and 0 transitions.
Iterating global reduction 4 with 4 rules applied. Total rules applied 1340 place count 22 transition count 30
Drop transitions (Redundant composition of simpler transitions.) removed 2 transitions
Redundant transition composition rules discarded 2 transitions
Iterating global reduction 4 with 2 rules applied. Total rules applied 1342 place count 22 transition count 28
Partial Free-agglomeration rule applied 1 times.
Drop transitions (Partial Free agglomeration) removed 1 transitions
Iterating global reduction 4 with 1 rules applied. Total rules applied 1343 place count 22 transition count 28
Reduce places removed 1 places and 1 transitions.
Iterating global reduction 4 with 1 rules applied. Total rules applied 1344 place count 21 transition count 27
Applied a total of 1344 rules in 112 ms. Remains 21 /720 variables (removed 699) and now considering 27/757 (removed 730) transitions.
Finished structural reductions in REACHABILITY mode , in 1 iterations and 123 ms. Remains : 21/720 places, 27/757 transitions.
RANDOM walk for 220 steps (11 resets) in 8 ms. (24 steps per ms) remains 0/1 properties
FORMULA GPUForwardProgress-PT-36b-ReachabilityFireability-2024-15 TRUE TECHNIQUES TOPOLOGICAL RANDOM_WALK
All properties solved without resorting to model-checking.
Total runtime 8956 ms.
ITS solved all properties within timeout

BK_STOP 1717199141264

--------------------
content from stderr:

+ ulimit -s 65536
+ [[ -z '' ]]
+ export LTSMIN_MEM_SIZE=8589934592
+ LTSMIN_MEM_SIZE=8589934592
+ export PYTHONPATH=/home/mcc/BenchKit/itstools/pylibs
+ PYTHONPATH=/home/mcc/BenchKit/itstools/pylibs
+ export LD_LIBRARY_PATH=/home/mcc/BenchKit/itstools/pylibs:
+ LD_LIBRARY_PATH=/home/mcc/BenchKit/itstools/pylibs:
++ sed s/.jar//
++ perl -pe 's/.*\.//g'
++ ls /home/mcc/BenchKit/bin//../reducer/bin//../../itstools//itstools/plugins/fr.lip6.move.gal.application.pnmcc_1.0.0.202405141337.jar
+ VERSION=202405141337
+ echo 'Running Version 202405141337'
+ /home/mcc/BenchKit/bin//../reducer/bin//../../itstools//itstools/its-tools -pnfolder /home/mcc/execution -examination ReachabilityFireability -timeout 360 -rebuildPNML

Sequence of Actions to be Executed by the VM

This is useful if one wants to reexecute the tool in the VM from the submitted image disk.

set -x
# this is for BenchKit: configuration of major elements for the test
export BK_INPUT="GPUForwardProgress-PT-36b"
export BK_EXAMINATION="ReachabilityFireability"
export BK_TOOL="ltsminxred"
export BK_RESULT_DIR="/tmp/BK_RESULTS/OUTPUTS"
export BK_TIME_CONFINEMENT="3600"
export BK_MEMORY_CONFINEMENT="16384"
export BK_BIN_PATH="/home/mcc/BenchKit/bin/"

# this is specific to your benchmark or test

export BIN_DIR="$HOME/BenchKit/bin"

# remove the execution directoty if it exists (to avoid increse of .vmdk images)
if [ -d execution ] ; then
rm -rf execution
fi

# this is for BenchKit: explicit launching of the test
echo "====================================================================="
echo " Generated by BenchKit 2-5568"
echo " Executing tool ltsminxred"
echo " Input is GPUForwardProgress-PT-36b, examination is ReachabilityFireability"
echo " Time confinement is $BK_TIME_CONFINEMENT seconds"
echo " Memory confinement is 16384 MBytes"
echo " Number of cores is 4"
echo " Run identifier is r496-tall-171640603800607"
echo "====================================================================="
echo
echo "--------------------"
echo "preparation of the directory to be used:"

tar xzf /home/mcc/BenchKit/INPUTS/GPUForwardProgress-PT-36b.tgz
mv GPUForwardProgress-PT-36b execution
cd execution
if [ "ReachabilityFireability" = "ReachabilityDeadlock" ] || [ "ReachabilityFireability" = "UpperBounds" ] || [ "ReachabilityFireability" = "QuasiLiveness" ] || [ "ReachabilityFireability" = "StableMarking" ] || [ "ReachabilityFireability" = "Liveness" ] || [ "ReachabilityFireability" = "OneSafe" ] || [ "ReachabilityFireability" = "StateSpace" ]; then
rm -f GenericPropertiesVerdict.xml
fi
pwd
ls -lh

echo
echo "--------------------"
echo "content from stdout:"
echo
echo "=== Data for post analysis generated by BenchKit (invocation template)"
echo
if [ "ReachabilityFireability" = "UpperBounds" ] ; then
echo "The expected result is a vector of positive values"
echo NUM_VECTOR
elif [ "ReachabilityFireability" != "StateSpace" ] ; then
echo "The expected result is a vector of booleans"
echo BOOL_VECTOR
else
echo "no data necessary for post analysis"
fi
echo
if [ -f "ReachabilityFireability.txt" ] ; then
echo "here is the order used to build the result vector(from text file)"
for x in $(grep Property ReachabilityFireability.txt | cut -d ' ' -f 2 | sort -u) ; do
echo "FORMULA_NAME $x"
done
elif [ -f "ReachabilityFireability.xml" ] ; then # for cunf (txt files deleted;-)
echo echo "here is the order used to build the result vector(from xml file)"
for x in $(grep '' ReachabilityFireability.xml | cut -d '>' -f 2 | cut -d '<' -f 1 | sort -u) ; do
echo "FORMULA_NAME $x"
done
elif [ "ReachabilityFireability" = "ReachabilityDeadlock" ] || [ "ReachabilityFireability" = "QuasiLiveness" ] || [ "ReachabilityFireability" = "StableMarking" ] || [ "ReachabilityFireability" = "Liveness" ] || [ "ReachabilityFireability" = "OneSafe" ] ; then
echo "FORMULA_NAME ReachabilityFireability"
fi
echo
echo "=== Now, execution of the tool begins"
echo
echo -n "BK_START "
date -u +%s%3N
echo
timeout -s 9 $BK_TIME_CONFINEMENT bash -c "/home/mcc/BenchKit/BenchKit_head.sh 2> STDERR ; echo ; echo -n \"BK_STOP \" ; date -u +%s%3N"
if [ $? -eq 137 ] ; then
echo
echo "BK_TIME_CONFINEMENT_REACHED"
fi
echo
echo "--------------------"
echo "content from stderr:"
echo
cat STDERR ;