YES Problem: purge(nil()) -> nil() purge(.(x,y)) -> .(x,purge(remove(x,y))) remove(x,nil()) -> nil() remove(x,.(y,z)) -> if(=(x,y),remove(x,z),.(y,remove(x,z))) Proof: DP Processor: DPs: purge#(.(x,y)) -> remove#(x,y) purge#(.(x,y)) -> purge#(remove(x,y)) remove#(x,.(y,z)) -> remove#(x,z) TRS: purge(nil()) -> nil() purge(.(x,y)) -> .(x,purge(remove(x,y))) remove(x,nil()) -> nil() remove(x,.(y,z)) -> if(=(x,y),remove(x,z),.(y,remove(x,z))) LPO Processor: argument filtering: pi(nil) = [] pi(purge) = [0] pi(.) = [1] pi(remove) = 1 pi(=) = 1 pi(if) = 2 pi(purge#) = 0 pi(remove#) = 1 precedence: purge > remove# ~ purge# ~ if ~ = ~ remove ~ . ~ nil problem: DPs: TRS: purge(nil()) -> nil() purge(.(x,y)) -> .(x,purge(remove(x,y))) remove(x,nil()) -> nil() remove(x,.(y,z)) -> if(=(x,y),remove(x,z),.(y,remove(x,z))) Qed