YES active____XYZmark__X__YZactive__XnilmarkXactive__nilXmarkXactiveandttXmarkXactiveisNePal__I__PImarkttactive__X1X2__activeX1X2active__X1X2__X1activeX2activeandX1X2andactiveX1X2activeisNePalXisNePalactiveX__markX1X2mark__X1X2__X1markX2mark__X1X2andmarkX1X2markandX1X2isNePalmarkXmarkisNePalXproper__X1X2__properX1properX2properniloknilproperandX1X2andproperX1properX2properttokttproperisNePalXisNePalproperX__okX1okX2ok__X1X2andokX1okX2okandX1X2isNePalokXokisNePalXtopmarkXtopproperXtopokXtopactiveX2.11active111__22112mark111nil00and211112tt00isNePal121proper111ok111top111active____XYZmark__X__YZactive__XnilmarkXactive__nilXmarkXactiveisNePal__I__PImarkttactive__X1X2__activeX1X2active__X1X2__X1activeX2activeandX1X2andactiveX1X2activeisNePalXisNePalactiveX__markX1X2mark__X1X2__X1markX2mark__X1X2andmarkX1X2markandX1X2isNePalmarkXmarkisNePalXproper__X1X2__properX1properX2properniloknilproperandX1X2andproperX1properX2properttokttproperisNePalXisNePalproperX__okX1okX2ok__X1X2andokX1okX2okandX1X2isNePalokXokisNePalXtopmarkXtopproperXtopokXtopactiveX1active111__211112mark111nil00isNePal121tt00and22122proper111ok111top111active____XYZmark__X__YZactive__X1X2__activeX1X2active__X1X2__X1activeX2activeandX1X2andactiveX1X2activeisNePalXisNePalactiveX__markX1X2mark__X1X2__X1markX2mark__X1X2andmarkX1X2markandX1X2isNePalmarkXmarkisNePalXproper__X1X2__properX1properX2properniloknilproperandX1X2andproperX1properX2properttokttproperisNePalXisNePalproperX__okX1okX2ok__X1X2andokX1okX2okandX1X2isNePalokXokisNePalXtopmarkXtopproperXtopokXtopactiveX1active111__212112mark1111and22112isNePal121proper111nil00ok111tt00top121active____XYZmark__X__YZactive__X1X2__activeX1X2active__X1X2__X1activeX2activeandX1X2andactiveX1X2activeisNePalXisNePalactiveX__X1markX2mark__X1X2proper__X1X2__properX1properX2properniloknilproperandX1X2andproperX1properX2properttokttproperisNePalXisNePalproperX__okX1okX2ok__X1X2andokX1okX2okandX1X2isNePalokXokisNePalXtopokXtopactiveX1active1121__221112mark111and221112isNePal111proper1221nil00ok1221tt00top111activeisNePalXisNePalactiveX__X1markX2mark__X1X2proper__X1X2__properX1properX2properniloknilproperandX1X2andproperX1properX2properttokttproperisNePalXisNePalproperX__okX1okX2ok__X1X2andokX1okX2okandX1X2isNePalokXokisNePalX1active1121isNePal1221__222112mark111proper1121nil00ok1111and211112tt00__X1markX2mark__X1X2proper__X1X2__properX1properX2properniloknilproperandX1X2andproperX1properX2properttoktt1__222112mark111proper1121nil00ok111and222112tt02__X1markX2mark__X1X2proper__X1X2__properX1properX2properandX1X2andproperX1properX21mark101proper130__210and220AProVEAProVE Commit ID: 48fb2092695e11cc9f56e44b17a92a5f88ffb256 marcel 20180622 unpublished dirty Statistics for single proof: 100.00 % (8 real / 0 unknown / 0 assumptions / 8 total proof steps)http://aprove.informatik.rwth-aachen.deJohnDoe