./Ultimate.py --spec ../../sv-benchmarks/c/properties/unreach-call.prp --file ../../sv-benchmarks/c/hardware-verification-bv/btor2c-lazyMod.extinction.2.prop1-func-interl.c --full-output --architecture 64bit -------------------------------------------------------------------------------- Checking for ERROR reachability Using default analysis Version 6b4ec56b Calling Ultimate with: /usr/lib/jvm/java-11-openjdk-amd64/bin/java -Dosgi.configuration.area=/tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/data/config -Xmx15G -Xms4m -jar /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/plugins/org.eclipse.equinox.launcher_1.5.800.v20200727-1323.jar -data @noDefault -ultimatedata /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/data -tc /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/config/KojakReach.xml -i ../../sv-benchmarks/c/hardware-verification-bv/btor2c-lazyMod.extinction.2.prop1-func-interl.c -s /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/config/svcomp-Reach-64bit-Kojak_Default.epf --cacsl2boogietranslator.entry.function main --witnessprinter.witness.directory /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ --witnessprinter.witness.filename witness.graphml --witnessprinter.write.witness.besides.input.file false --witnessprinter.graph.data.specification CHECK( init(main()), LTL(G ! call(reach_error())) ) --witnessprinter.graph.data.producer Kojak --witnessprinter.graph.data.architecture 64bit --witnessprinter.graph.data.programhash 7a579b107ae8714a235da0a07f4e3e09efaade46d9c37c625c3a68292bc578b8 --- Real Ultimate output --- [0.001s][warning][os,container] Duplicate cpuset controllers detected. Picking /sys/fs/cgroup/cpuset, skipping /sys/fs/cgroup/cpuset. This is Ultimate 0.2.2-dev-6b4ec56 [2022-11-20 16:41:37,778 INFO L177 SettingsManager]: Resetting all preferences to default values... [2022-11-20 16:41:37,781 INFO L181 SettingsManager]: Resetting UltimateCore preferences to default values [2022-11-20 16:41:37,804 INFO L184 SettingsManager]: Ultimate Commandline Interface provides no preferences, ignoring... [2022-11-20 16:41:37,805 INFO L181 SettingsManager]: Resetting Boogie Preprocessor preferences to default values [2022-11-20 16:41:37,806 INFO L181 SettingsManager]: Resetting Boogie Procedure Inliner preferences to default values [2022-11-20 16:41:37,807 INFO L181 SettingsManager]: Resetting Abstract Interpretation preferences to default values [2022-11-20 16:41:37,810 INFO L181 SettingsManager]: Resetting LassoRanker preferences to default values [2022-11-20 16:41:37,811 INFO L181 SettingsManager]: Resetting Reaching Definitions preferences to default values [2022-11-20 16:41:37,813 INFO L181 SettingsManager]: Resetting SyntaxChecker preferences to default values [2022-11-20 16:41:37,814 INFO L181 SettingsManager]: Resetting Sifa preferences to default values [2022-11-20 16:41:37,815 INFO L184 SettingsManager]: Büchi Program Product provides no preferences, ignoring... [2022-11-20 16:41:37,816 INFO L181 SettingsManager]: Resetting LTL2Aut preferences to default values [2022-11-20 16:41:37,817 INFO L181 SettingsManager]: Resetting PEA to Boogie preferences to default values [2022-11-20 16:41:37,819 INFO L181 SettingsManager]: Resetting BlockEncodingV2 preferences to default values [2022-11-20 16:41:37,820 INFO L181 SettingsManager]: Resetting ChcToBoogie preferences to default values [2022-11-20 16:41:37,821 INFO L181 SettingsManager]: Resetting AutomataScriptInterpreter preferences to default values [2022-11-20 16:41:37,822 INFO L181 SettingsManager]: Resetting BuchiAutomizer preferences to default values [2022-11-20 16:41:37,824 INFO L181 SettingsManager]: Resetting CACSL2BoogieTranslator preferences to default values [2022-11-20 16:41:37,826 INFO L181 SettingsManager]: Resetting CodeCheck preferences to default values [2022-11-20 16:41:37,837 INFO L181 SettingsManager]: Resetting InvariantSynthesis preferences to default values [2022-11-20 16:41:37,838 INFO L181 SettingsManager]: Resetting RCFGBuilder preferences to default values [2022-11-20 16:41:37,839 INFO L181 SettingsManager]: Resetting Referee preferences to default values [2022-11-20 16:41:37,840 INFO L181 SettingsManager]: Resetting TraceAbstraction preferences to default values [2022-11-20 16:41:37,844 INFO L184 SettingsManager]: TraceAbstractionConcurrent provides no preferences, ignoring... [2022-11-20 16:41:37,844 INFO L184 SettingsManager]: TraceAbstractionWithAFAs provides no preferences, ignoring... [2022-11-20 16:41:37,845 INFO L181 SettingsManager]: Resetting TreeAutomizer preferences to default values [2022-11-20 16:41:37,845 INFO L181 SettingsManager]: Resetting IcfgToChc preferences to default values [2022-11-20 16:41:37,846 INFO L181 SettingsManager]: Resetting IcfgTransformer preferences to default values [2022-11-20 16:41:37,847 INFO L184 SettingsManager]: ReqToTest provides no preferences, ignoring... [2022-11-20 16:41:37,847 INFO L181 SettingsManager]: Resetting Boogie Printer preferences to default values [2022-11-20 16:41:37,848 INFO L181 SettingsManager]: Resetting ChcSmtPrinter preferences to default values [2022-11-20 16:41:37,849 INFO L181 SettingsManager]: Resetting ReqPrinter preferences to default values [2022-11-20 16:41:37,850 INFO L181 SettingsManager]: Resetting Witness Printer preferences to default values [2022-11-20 16:41:37,851 INFO L184 SettingsManager]: Boogie PL CUP Parser provides no preferences, ignoring... [2022-11-20 16:41:37,851 INFO L181 SettingsManager]: Resetting CDTParser preferences to default values [2022-11-20 16:41:37,852 INFO L184 SettingsManager]: AutomataScriptParser provides no preferences, ignoring... [2022-11-20 16:41:37,852 INFO L184 SettingsManager]: ReqParser provides no preferences, ignoring... [2022-11-20 16:41:37,852 INFO L181 SettingsManager]: Resetting SmtParser preferences to default values [2022-11-20 16:41:37,853 INFO L181 SettingsManager]: Resetting Witness Parser preferences to default values [2022-11-20 16:41:37,869 INFO L188 SettingsManager]: Finished resetting all preferences to default values... [2022-11-20 16:41:37,870 INFO L101 SettingsManager]: Beginning loading settings from /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/config/svcomp-Reach-64bit-Kojak_Default.epf [2022-11-20 16:41:37,889 INFO L113 SettingsManager]: Loading preferences was successful [2022-11-20 16:41:37,890 INFO L115 SettingsManager]: Preferences different from defaults after loading the file: [2022-11-20 16:41:37,890 INFO L136 SettingsManager]: Preferences of Boogie Procedure Inliner differ from their defaults: [2022-11-20 16:41:37,891 INFO L138 SettingsManager]: * Ignore calls to procedures called more than once=ALWAYS [2022-11-20 16:41:37,891 INFO L136 SettingsManager]: Preferences of BlockEncodingV2 differ from their defaults: [2022-11-20 16:41:37,891 INFO L138 SettingsManager]: * Create parallel compositions if possible=false [2022-11-20 16:41:37,892 INFO L136 SettingsManager]: Preferences of CACSL2BoogieTranslator differ from their defaults: [2022-11-20 16:41:37,892 INFO L138 SettingsManager]: * Overapproximate operations on floating types=true [2022-11-20 16:41:37,892 INFO L138 SettingsManager]: * Check division by zero=IGNORE [2022-11-20 16:41:37,892 INFO L138 SettingsManager]: * Pointer to allocated memory at dereference=IGNORE [2022-11-20 16:41:37,893 INFO L138 SettingsManager]: * If two pointers are subtracted or compared they have the same base address=IGNORE [2022-11-20 16:41:37,893 INFO L138 SettingsManager]: * Check array bounds for arrays that are off heap=IGNORE [2022-11-20 16:41:37,893 INFO L138 SettingsManager]: * Check if freed pointer was valid=false [2022-11-20 16:41:37,893 INFO L138 SettingsManager]: * Use constant arrays=true [2022-11-20 16:41:37,893 INFO L138 SettingsManager]: * Pointer base address is valid at dereference=IGNORE [2022-11-20 16:41:37,894 INFO L136 SettingsManager]: Preferences of CodeCheck differ from their defaults: [2022-11-20 16:41:37,894 INFO L138 SettingsManager]: * Timeout in seconds=1000000 [2022-11-20 16:41:37,894 INFO L136 SettingsManager]: Preferences of RCFGBuilder differ from their defaults: [2022-11-20 16:41:37,894 INFO L138 SettingsManager]: * Command for external solver=z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:10000 [2022-11-20 16:41:37,895 INFO L136 SettingsManager]: Preferences of TraceAbstraction differ from their defaults: [2022-11-20 16:41:37,895 INFO L138 SettingsManager]: * Compute Interpolants along a Counterexample=FPandBP [2022-11-20 16:41:37,895 INFO L138 SettingsManager]: * Positions where we compute the Hoare Annotation=LoopsAndPotentialCycles [2022-11-20 16:41:37,895 INFO L138 SettingsManager]: * Trace refinement strategy=PENGUIN [2022-11-20 16:41:37,895 INFO L138 SettingsManager]: * Command for external solver=z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in [2022-11-20 16:41:37,896 INFO L138 SettingsManager]: * Compute Hoare Annotation of negated interpolant automaton, abstraction and CFG=true [2022-11-20 16:41:37,896 INFO L138 SettingsManager]: * SMT solver=External_ModelsAndUnsatCoreMode WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by com.sun.xml.bind.v2.runtime.reflect.opt.Injector$1 (file:/tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/plugins/com.sun.xml.bind_2.2.0.v201505121915.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int) WARNING: Please consider reporting this to the maintainers of com.sun.xml.bind.v2.runtime.reflect.opt.Injector$1 WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release Applying setting for plugin de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator: Entry function -> main Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Witness directory -> /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Witness filename -> witness.graphml Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Write witness besides input file -> false Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Graph data specification -> CHECK( init(main()), LTL(G ! call(reach_error())) ) Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Graph data producer -> Kojak Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Graph data architecture -> 64bit Applying setting for plugin de.uni_freiburg.informatik.ultimate.witnessprinter: Graph data programhash -> 7a579b107ae8714a235da0a07f4e3e09efaade46d9c37c625c3a68292bc578b8 [2022-11-20 16:41:38,181 INFO L75 nceAwareModelManager]: Repository-Root is: /tmp [2022-11-20 16:41:38,223 INFO L261 ainManager$Toolchain]: [Toolchain 1]: Applicable parser(s) successfully (re)initialized [2022-11-20 16:41:38,226 INFO L217 ainManager$Toolchain]: [Toolchain 1]: Toolchain selected. [2022-11-20 16:41:38,227 INFO L271 PluginConnector]: Initializing CDTParser... [2022-11-20 16:41:38,228 INFO L275 PluginConnector]: CDTParser initialized [2022-11-20 16:41:38,229 INFO L432 ainManager$Toolchain]: [Toolchain 1]: Parsing single file: /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/../../sv-benchmarks/c/hardware-verification-bv/btor2c-lazyMod.extinction.2.prop1-func-interl.c [2022-11-20 16:41:41,229 INFO L500 CDTParser]: Created temporary CDT project at NULL [2022-11-20 16:41:41,684 INFO L351 CDTParser]: Found 1 translation units. [2022-11-20 16:41:41,686 INFO L172 CDTParser]: Scanning /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/sv-benchmarks/c/hardware-verification-bv/btor2c-lazyMod.extinction.2.prop1-func-interl.c [2022-11-20 16:41:41,728 INFO L394 CDTParser]: About to delete temporary CDT project at /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/data/a815c9e73/b1b08a230148462e81a9609d5edbed79/FLAG91fc92f1d [2022-11-20 16:41:41,747 INFO L402 CDTParser]: Successfully deleted /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/data/a815c9e73/b1b08a230148462e81a9609d5edbed79 [2022-11-20 16:41:41,751 INFO L299 ainManager$Toolchain]: ####################### [Toolchain 1] ####################### [2022-11-20 16:41:41,753 INFO L131 ToolchainWalker]: Walking toolchain with 6 elements. [2022-11-20 16:41:41,758 INFO L113 PluginConnector]: ------------------------CACSL2BoogieTranslator---------------------------- [2022-11-20 16:41:41,759 INFO L271 PluginConnector]: Initializing CACSL2BoogieTranslator... [2022-11-20 16:41:41,762 INFO L275 PluginConnector]: CACSL2BoogieTranslator initialized [2022-11-20 16:41:41,763 INFO L185 PluginConnector]: Executing the observer ACSLObjectContainerObserver from plugin CACSL2BoogieTranslator for "CDTParser AST 20.11 04:41:41" (1/1) ... [2022-11-20 16:41:41,764 INFO L205 PluginConnector]: Invalid model from CACSL2BoogieTranslator for observer de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator.ACSLObjectContainerObserver@6caf57a4 and model type de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:41, skipping insertion in model container [2022-11-20 16:41:41,764 INFO L185 PluginConnector]: Executing the observer CACSL2BoogieTranslatorObserver from plugin CACSL2BoogieTranslator for "CDTParser AST 20.11 04:41:41" (1/1) ... [2022-11-20 16:41:41,772 INFO L145 MainTranslator]: Starting translation in SV-COMP mode [2022-11-20 16:41:41,893 INFO L178 MainTranslator]: Built tables and reachable declarations [2022-11-20 16:41:42,162 WARN L237 ndardFunctionHandler]: Function reach_error is already implemented but we override the implementation for the call at /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/sv-benchmarks/c/hardware-verification-bv/btor2c-lazyMod.extinction.2.prop1-func-interl.c[1014,1027] [2022-11-20 16:41:43,002 INFO L210 PostProcessor]: Analyzing one entry point: main [2022-11-20 16:41:43,008 INFO L203 MainTranslator]: Completed pre-run [2022-11-20 16:41:43,020 WARN L237 ndardFunctionHandler]: Function reach_error is already implemented but we override the implementation for the call at /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/sv-benchmarks/c/hardware-verification-bv/btor2c-lazyMod.extinction.2.prop1-func-interl.c[1014,1027] [2022-11-20 16:41:43,444 INFO L210 PostProcessor]: Analyzing one entry point: main [2022-11-20 16:41:43,457 INFO L208 MainTranslator]: Completed translation [2022-11-20 16:41:43,457 INFO L202 PluginConnector]: Adding new model de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43 WrapperNode [2022-11-20 16:41:43,458 INFO L132 PluginConnector]: ------------------------ END CACSL2BoogieTranslator---------------------------- [2022-11-20 16:41:43,459 INFO L113 PluginConnector]: ------------------------Boogie Procedure Inliner---------------------------- [2022-11-20 16:41:43,459 INFO L271 PluginConnector]: Initializing Boogie Procedure Inliner... [2022-11-20 16:41:43,459 INFO L275 PluginConnector]: Boogie Procedure Inliner initialized [2022-11-20 16:41:43,468 INFO L185 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Procedure Inliner for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:43,562 INFO L185 PluginConnector]: Executing the observer Inliner from plugin Boogie Procedure Inliner for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:43,967 INFO L138 Inliner]: procedures = 11, calls = 3, calls flagged for inlining = 3, calls inlined = 3, statements flattened = 6925 [2022-11-20 16:41:43,968 INFO L132 PluginConnector]: ------------------------ END Boogie Procedure Inliner---------------------------- [2022-11-20 16:41:43,968 INFO L113 PluginConnector]: ------------------------Boogie Preprocessor---------------------------- [2022-11-20 16:41:43,969 INFO L271 PluginConnector]: Initializing Boogie Preprocessor... [2022-11-20 16:41:43,969 INFO L275 PluginConnector]: Boogie Preprocessor initialized [2022-11-20 16:41:43,978 INFO L185 PluginConnector]: Executing the observer EnsureBoogieModelObserver from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:43,979 INFO L185 PluginConnector]: Executing the observer TypeChecker from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,051 INFO L185 PluginConnector]: Executing the observer ConstExpander from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,052 INFO L185 PluginConnector]: Executing the observer StructExpander from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,289 INFO L185 PluginConnector]: Executing the observer UnstructureCode from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,308 INFO L185 PluginConnector]: Executing the observer FunctionInliner from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,332 INFO L185 PluginConnector]: Executing the observer LTLStepAnnotator from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,351 INFO L185 PluginConnector]: Executing the observer BoogieSymbolTableConstructor from plugin Boogie Preprocessor for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,410 INFO L132 PluginConnector]: ------------------------ END Boogie Preprocessor---------------------------- [2022-11-20 16:41:44,412 INFO L113 PluginConnector]: ------------------------RCFGBuilder---------------------------- [2022-11-20 16:41:44,412 INFO L271 PluginConnector]: Initializing RCFGBuilder... [2022-11-20 16:41:44,413 INFO L275 PluginConnector]: RCFGBuilder initialized [2022-11-20 16:41:44,414 INFO L185 PluginConnector]: Executing the observer RCFGBuilderObserver from plugin RCFGBuilder for "de.uni_freiburg.informatik.ultimate.plugins.generator.cacsl2boogietranslator AST 20.11 04:41:43" (1/1) ... [2022-11-20 16:41:44,420 INFO L173 SolverBuilder]: Constructing external solver with command: z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:10000 [2022-11-20 16:41:44,432 INFO L189 MonitoredProcess]: No working directory specified, using /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/z3 [2022-11-20 16:41:44,449 INFO L229 MonitoredProcess]: Starting monitored process 1 with /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:10000 (exit command is (exit), workingDir is null) [2022-11-20 16:41:44,475 INFO L327 MonitoredProcess]: [MP /tmp/vcloud_worker_vcloud-master_on_vcloud-master/run_dir_2826690e-c702-471c-b25f-7dd340655402/bin/ukojak-pZX7IvK2PQ/z3 SMTLIB2_COMPLIANT=true -memory:2024 -smt2 -in -t:10000 (1)] Waiting until timeout for monitored process [2022-11-20 16:41:44,496 INFO L130 BoogieDeclarations]: Found specification of procedure ULTIMATE.start [2022-11-20 16:41:44,497 INFO L138 BoogieDeclarations]: Found implementation of procedure ULTIMATE.start [2022-11-20 16:41:45,903 INFO L235 CfgBuilder]: Building ICFG [2022-11-20 16:41:45,905 INFO L261 CfgBuilder]: Building CFG for each procedure with an implementation