YES append@l1@l2append#1@l1@l2append#1::@x@xs@l2::@xappend@xs@l2append#1nil@l2@l2subtrees@tsubtrees#1@tsubtrees#1leafnilsubtrees#1node@x@t1@t2subtrees#2subtrees@t1@t1@t2@xsubtrees#2@l1@t1@t2@xsubtrees#3subtrees@t2@l1@t1@t2@xsubtrees#3@l2@l1@t1@t2@x::node@x@t1@t2append@l1@l22.1append21append#121::20nil03subtrees13subtrees#113leaf04node32subtrees#243subtrees#352append212append#1212::212nil0subtrees11subtrees#111leaf0node3123subtrees#243124subtrees#3512345append@l1@l2append#1@l1@l2subtrees@tsubtrees#1@t1subtrees131subtrees#1121append210append#1200AProVEAProVE Commit ID: 48fb2092695e11cc9f56e44b17a92a5f88ffb256 marcel 20180622 unpublished dirty Statistics for single proof: 100.00 % (3 real / 0 unknown / 0 assumptions / 3 total proof steps)http://aprove.informatik.rwth-aachen.deJohnDoe