YES We show the termination of the TRS R: or(x,x) -> x and(x,x) -> x not(not(x)) -> x not(and(x,y)) -> or(not(x),not(y)) not(or(x,y)) -> and(not(x),not(y)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: not#(and(x,y)) -> or#(not(x),not(y)) p2: not#(and(x,y)) -> not#(x) p3: not#(and(x,y)) -> not#(y) p4: not#(or(x,y)) -> and#(not(x),not(y)) p5: not#(or(x,y)) -> not#(x) p6: not#(or(x,y)) -> not#(y) and R consists of: r1: or(x,x) -> x r2: and(x,x) -> x r3: not(not(x)) -> x r4: not(and(x,y)) -> or(not(x),not(y)) r5: not(or(x,y)) -> and(not(x),not(y)) The estimated dependency graph contains the following SCCs: {p2, p3, p5, p6} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: not#(and(x,y)) -> not#(x) p2: not#(or(x,y)) -> not#(y) p3: not#(or(x,y)) -> not#(x) p4: not#(and(x,y)) -> not#(y) and R consists of: r1: or(x,x) -> x r2: and(x,x) -> x r3: not(not(x)) -> x r4: not(and(x,y)) -> or(not(x),not(y)) r5: not(or(x,y)) -> and(not(x),not(y)) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: not#_A(x1) = ((1,0),(1,0)) x1 + (1,2) and_A(x1,x2) = ((1,0),(1,1)) x1 + ((1,0),(0,0)) x2 + (2,3) or_A(x1,x2) = x1 + ((1,0),(0,0)) x2 + (2,1) precedence: not# = and = or partial status: pi(not#) = [] pi(and) = [] pi(or) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: not#_A(x1) = (1,2) and_A(x1,x2) = (0,1) or_A(x1,x2) = ((1,0),(0,0)) x1 + (2,3) precedence: not# = and = or partial status: pi(not#) = [] pi(and) = [] pi(or) = [] The next rules are strictly ordered: p1, p2, p3, p4 We remove them from the problem. Then no dependency pair remains.