0.075 * [progress]: [Phase 1 of 3] Setting up. 0.001 * * * [progress]: [1/2] Preparing points 0.023 * * * [progress]: [2/2] Setting up program. 0.025 * [progress]: [Phase 2 of 3] Improving. 0.026 * [simplify]: Simplifying: (/ (- x (* y z)) (- t (* a z))) 0.026 * * [simplify]: Extracting # 0 : cost 0 0.026 * * [simplify]: Extracting # 1 : cost 0 0.026 * * [simplify]: Extracting # 2 : cost 0 0.026 * * [simplify]: Extracting # 3 : cost 0 0.026 * * [simplify]: Extracting # 4 : cost 0 0.026 * * [simplify]: Extracting # 5 : cost 0 0.026 * * [simplify]: iteration 0 : 10 enodes (cost 11 ) 0.027 * * [simplify]: Extracting # 0 : cost 0 0.027 * * [simplify]: Extracting # 1 : cost 0 0.027 * * [simplify]: Extracting # 2 : cost 0 0.027 * * [simplify]: iteration 1 : 19 enodes (cost 11 ) 0.030 * * [simplify]: Extracting # 0 : cost 0 0.030 * * [simplify]: Extracting # 1 : cost 0 0.030 * * [simplify]: Extracting # 2 : cost 0 0.030 * * [simplify]: iteration 2 : 38 enodes (cost 11 ) 0.036 * * [simplify]: Extracting # 0 : cost 0 0.036 * * [simplify]: Extracting # 1 : cost 0 0.036 * * [simplify]: Extracting # 2 : cost 0 0.037 * * [simplify]: iteration 3 : 60 enodes (cost 11 ) 0.056 * * [simplify]: Extracting # 0 : cost 0 0.056 * * [simplify]: Extracting # 1 : cost 0 0.056 * * [simplify]: Extracting # 2 : cost 0 0.056 * * [simplify]: iteration 4 : 88 enodes (cost 11 ) 0.071 * * [simplify]: Extracting # 0 : cost 0 0.071 * * [simplify]: Extracting # 1 : cost 0 0.072 * * [simplify]: Extracting # 2 : cost 0 0.072 * * [simplify]: iteration 5 : 120 enodes (cost 11 ) 0.094 * * [simplify]: Extracting # 0 : cost 0 0.094 * * [simplify]: Extracting # 1 : cost 0 0.094 * * [simplify]: Extracting # 2 : cost 0 0.095 * * [simplify]: iteration 6 : 168 enodes (cost 11 ) 0.134 * * [simplify]: Extracting # 0 : cost 0 0.135 * * [simplify]: Extracting # 1 : cost 0 0.135 * * [simplify]: Extracting # 2 : cost 0 0.135 * * [simplify]: iteration 7 : 326 enodes (cost 11 ) 0.635 * * [simplify]: Extracting # 0 : cost 0 0.639 * * [simplify]: Extracting # 1 : cost 0 0.641 * * [simplify]: Extracting # 2 : cost 0 0.642 * * [simplify]: iteration 8 : 1124 enodes (cost 11 ) 6.358 * * [simplify]: Extracting # 0 : cost 0 6.371 * * [simplify]: Extracting # 1 : cost 0 6.375 * * [simplify]: Extracting # 2 : cost 0 6.378 * * [simplify]: Extracting # 3 : cost 0 6.381 * * [simplify]: Extracting # 4 : cost 0 6.385 * * [simplify]: iteration done: 5000 enodes (cost 11 ) 6.385 * [simplify]: Simplified to: (/ (- x (* y z)) (- t (* a z))) 6.385 * * [progress]: iteration 1 / 4 6.385 * * * [progress]: picking best candidate 6.388 * * * * [pick]: Picked # 6.388 * * * [progress]: localizing error 6.398 * * * [progress]: generating rewritten candidates 6.398 * * * * [progress]: [ 1 / 2 ] rewriting at (2) 6.434 * * * * [progress]: [ 2 / 2 ] rewriting at (2 1) 6.441 * * * [progress]: generating series expansions 6.441 * * * * [progress]: [ 1 / 2 ] generating series at (2) 6.442 * [backup-simplify]: Simplify (/ (- x (* y z)) (- t (* a z))) into (/ (- x (* z y)) (- t (* a z))) 6.442 * [approximate]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in (x y z t a) around 0 6.442 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in a 6.442 * [taylor]: Taking taylor expansion of (- x (* z y)) in a 6.442 * [taylor]: Taking taylor expansion of x in a 6.442 * [backup-simplify]: Simplify x into x 6.442 * [taylor]: Taking taylor expansion of (* z y) in a 6.442 * [taylor]: Taking taylor expansion of z in a 6.442 * [backup-simplify]: Simplify z into z 6.442 * [taylor]: Taking taylor expansion of y in a 6.442 * [backup-simplify]: Simplify y into y 6.442 * [taylor]: Taking taylor expansion of (- t (* a z)) in a 6.442 * [taylor]: Taking taylor expansion of t in a 6.442 * [backup-simplify]: Simplify t into t 6.442 * [taylor]: Taking taylor expansion of (* a z) in a 6.442 * [taylor]: Taking taylor expansion of a in a 6.442 * [backup-simplify]: Simplify 0 into 0 6.442 * [backup-simplify]: Simplify 1 into 1 6.442 * [taylor]: Taking taylor expansion of z in a 6.442 * [backup-simplify]: Simplify z into z 6.442 * [backup-simplify]: Simplify (* z y) into (* z y) 6.442 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.442 * [backup-simplify]: Simplify (+ x (- (* z y))) into (- x (* z y)) 6.442 * [backup-simplify]: Simplify (* 0 z) into 0 6.443 * [backup-simplify]: Simplify (- 0) into 0 6.443 * [backup-simplify]: Simplify (+ t 0) into t 6.443 * [backup-simplify]: Simplify (/ (- x (* z y)) t) into (/ (- x (* z y)) t) 6.443 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in t 6.443 * [taylor]: Taking taylor expansion of (- x (* z y)) in t 6.443 * [taylor]: Taking taylor expansion of x in t 6.443 * [backup-simplify]: Simplify x into x 6.443 * [taylor]: Taking taylor expansion of (* z y) in t 6.443 * [taylor]: Taking taylor expansion of z in t 6.443 * [backup-simplify]: Simplify z into z 6.443 * [taylor]: Taking taylor expansion of y in t 6.443 * [backup-simplify]: Simplify y into y 6.443 * [taylor]: Taking taylor expansion of (- t (* a z)) in t 6.443 * [taylor]: Taking taylor expansion of t in t 6.443 * [backup-simplify]: Simplify 0 into 0 6.443 * [backup-simplify]: Simplify 1 into 1 6.443 * [taylor]: Taking taylor expansion of (* a z) in t 6.443 * [taylor]: Taking taylor expansion of a in t 6.443 * [backup-simplify]: Simplify a into a 6.443 * [taylor]: Taking taylor expansion of z in t 6.443 * [backup-simplify]: Simplify z into z 6.443 * [backup-simplify]: Simplify (* z y) into (* z y) 6.443 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.443 * [backup-simplify]: Simplify (+ x (- (* z y))) into (- x (* z y)) 6.443 * [backup-simplify]: Simplify (* a z) into (* a z) 6.443 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.443 * [backup-simplify]: Simplify (+ 0 (- (* a z))) into (- (* a z)) 6.443 * [backup-simplify]: Simplify (/ (- x (* z y)) (- (* a z))) into (* -1 (/ (- x (* z y)) (* a z))) 6.444 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in z 6.444 * [taylor]: Taking taylor expansion of (- x (* z y)) in z 6.444 * [taylor]: Taking taylor expansion of x in z 6.444 * [backup-simplify]: Simplify x into x 6.444 * [taylor]: Taking taylor expansion of (* z y) in z 6.444 * [taylor]: Taking taylor expansion of z in z 6.444 * [backup-simplify]: Simplify 0 into 0 6.444 * [backup-simplify]: Simplify 1 into 1 6.444 * [taylor]: Taking taylor expansion of y in z 6.444 * [backup-simplify]: Simplify y into y 6.444 * [taylor]: Taking taylor expansion of (- t (* a z)) in z 6.444 * [taylor]: Taking taylor expansion of t in z 6.444 * [backup-simplify]: Simplify t into t 6.444 * [taylor]: Taking taylor expansion of (* a z) in z 6.444 * [taylor]: Taking taylor expansion of a in z 6.444 * [backup-simplify]: Simplify a into a 6.444 * [taylor]: Taking taylor expansion of z in z 6.444 * [backup-simplify]: Simplify 0 into 0 6.444 * [backup-simplify]: Simplify 1 into 1 6.444 * [backup-simplify]: Simplify (* 0 y) into 0 6.444 * [backup-simplify]: Simplify (- 0) into 0 6.444 * [backup-simplify]: Simplify (+ x 0) into x 6.444 * [backup-simplify]: Simplify (* a 0) into 0 6.444 * [backup-simplify]: Simplify (- 0) into 0 6.445 * [backup-simplify]: Simplify (+ t 0) into t 6.445 * [backup-simplify]: Simplify (/ x t) into (/ x t) 6.445 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in y 6.445 * [taylor]: Taking taylor expansion of (- x (* z y)) in y 6.445 * [taylor]: Taking taylor expansion of x in y 6.445 * [backup-simplify]: Simplify x into x 6.445 * [taylor]: Taking taylor expansion of (* z y) in y 6.445 * [taylor]: Taking taylor expansion of z in y 6.445 * [backup-simplify]: Simplify z into z 6.445 * [taylor]: Taking taylor expansion of y in y 6.445 * [backup-simplify]: Simplify 0 into 0 6.445 * [backup-simplify]: Simplify 1 into 1 6.445 * [taylor]: Taking taylor expansion of (- t (* a z)) in y 6.445 * [taylor]: Taking taylor expansion of t in y 6.445 * [backup-simplify]: Simplify t into t 6.445 * [taylor]: Taking taylor expansion of (* a z) in y 6.445 * [taylor]: Taking taylor expansion of a in y 6.445 * [backup-simplify]: Simplify a into a 6.445 * [taylor]: Taking taylor expansion of z in y 6.445 * [backup-simplify]: Simplify z into z 6.445 * [backup-simplify]: Simplify (* z 0) into 0 6.445 * [backup-simplify]: Simplify (- 0) into 0 6.445 * [backup-simplify]: Simplify (+ x 0) into x 6.445 * [backup-simplify]: Simplify (* a z) into (* a z) 6.445 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.445 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.445 * [backup-simplify]: Simplify (/ x (- t (* a z))) into (/ x (- t (* a z))) 6.445 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in x 6.445 * [taylor]: Taking taylor expansion of (- x (* z y)) in x 6.445 * [taylor]: Taking taylor expansion of x in x 6.445 * [backup-simplify]: Simplify 0 into 0 6.446 * [backup-simplify]: Simplify 1 into 1 6.446 * [taylor]: Taking taylor expansion of (* z y) in x 6.446 * [taylor]: Taking taylor expansion of z in x 6.446 * [backup-simplify]: Simplify z into z 6.446 * [taylor]: Taking taylor expansion of y in x 6.446 * [backup-simplify]: Simplify y into y 6.446 * [taylor]: Taking taylor expansion of (- t (* a z)) in x 6.446 * [taylor]: Taking taylor expansion of t in x 6.446 * [backup-simplify]: Simplify t into t 6.446 * [taylor]: Taking taylor expansion of (* a z) in x 6.446 * [taylor]: Taking taylor expansion of a in x 6.446 * [backup-simplify]: Simplify a into a 6.446 * [taylor]: Taking taylor expansion of z in x 6.446 * [backup-simplify]: Simplify z into z 6.446 * [backup-simplify]: Simplify (* z y) into (* z y) 6.446 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.446 * [backup-simplify]: Simplify (+ 0 (- (* z y))) into (- (* z y)) 6.446 * [backup-simplify]: Simplify (* a z) into (* a z) 6.446 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.446 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.446 * [backup-simplify]: Simplify (/ (- (* z y)) (- t (* a z))) into (* -1 (/ (* z y) (- t (* a z)))) 6.446 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in x 6.446 * [taylor]: Taking taylor expansion of (- x (* z y)) in x 6.446 * [taylor]: Taking taylor expansion of x in x 6.446 * [backup-simplify]: Simplify 0 into 0 6.446 * [backup-simplify]: Simplify 1 into 1 6.446 * [taylor]: Taking taylor expansion of (* z y) in x 6.446 * [taylor]: Taking taylor expansion of z in x 6.446 * [backup-simplify]: Simplify z into z 6.446 * [taylor]: Taking taylor expansion of y in x 6.446 * [backup-simplify]: Simplify y into y 6.446 * [taylor]: Taking taylor expansion of (- t (* a z)) in x 6.446 * [taylor]: Taking taylor expansion of t in x 6.446 * [backup-simplify]: Simplify t into t 6.446 * [taylor]: Taking taylor expansion of (* a z) in x 6.446 * [taylor]: Taking taylor expansion of a in x 6.446 * [backup-simplify]: Simplify a into a 6.446 * [taylor]: Taking taylor expansion of z in x 6.446 * [backup-simplify]: Simplify z into z 6.446 * [backup-simplify]: Simplify (* z y) into (* z y) 6.446 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.447 * [backup-simplify]: Simplify (+ 0 (- (* z y))) into (- (* z y)) 6.447 * [backup-simplify]: Simplify (* a z) into (* a z) 6.447 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.447 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.447 * [backup-simplify]: Simplify (/ (- (* z y)) (- t (* a z))) into (* -1 (/ (* z y) (- t (* a z)))) 6.447 * [taylor]: Taking taylor expansion of (* -1 (/ (* z y) (- t (* a z)))) in y 6.447 * [taylor]: Taking taylor expansion of -1 in y 6.447 * [backup-simplify]: Simplify -1 into -1 6.447 * [taylor]: Taking taylor expansion of (/ (* z y) (- t (* a z))) in y 6.447 * [taylor]: Taking taylor expansion of (* z y) in y 6.447 * [taylor]: Taking taylor expansion of z in y 6.447 * [backup-simplify]: Simplify z into z 6.447 * [taylor]: Taking taylor expansion of y in y 6.447 * [backup-simplify]: Simplify 0 into 0 6.447 * [backup-simplify]: Simplify 1 into 1 6.447 * [taylor]: Taking taylor expansion of (- t (* a z)) in y 6.447 * [taylor]: Taking taylor expansion of t in y 6.447 * [backup-simplify]: Simplify t into t 6.447 * [taylor]: Taking taylor expansion of (* a z) in y 6.447 * [taylor]: Taking taylor expansion of a in y 6.447 * [backup-simplify]: Simplify a into a 6.447 * [taylor]: Taking taylor expansion of z in y 6.447 * [backup-simplify]: Simplify z into z 6.447 * [backup-simplify]: Simplify (* z 0) into 0 6.447 * [backup-simplify]: Simplify (+ (* z 1) (* 0 0)) into z 6.448 * [backup-simplify]: Simplify (* a z) into (* a z) 6.448 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.448 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.448 * [backup-simplify]: Simplify (/ z (- t (* a z))) into (/ z (- t (* a z))) 6.448 * [backup-simplify]: Simplify (+ (* z 0) (* 0 y)) into 0 6.448 * [backup-simplify]: Simplify (- 0) into 0 6.448 * [backup-simplify]: Simplify (+ 1 0) into 1 6.448 * [backup-simplify]: Simplify (+ (* a 0) (* 0 z)) into 0 6.449 * [backup-simplify]: Simplify (- 0) into 0 6.449 * [backup-simplify]: Simplify (+ 0 0) into 0 6.449 * [backup-simplify]: Simplify (- (/ 1 (- t (* a z))) (+ (* (* -1 (/ (* z y) (- t (* a z)))) (/ 0 (- t (* a z)))))) into (/ 1 (- t (* a z))) 6.449 * [taylor]: Taking taylor expansion of (/ 1 (- t (* a z))) in y 6.449 * [taylor]: Taking taylor expansion of (- t (* a z)) in y 6.449 * [taylor]: Taking taylor expansion of t in y 6.449 * [backup-simplify]: Simplify t into t 6.449 * [taylor]: Taking taylor expansion of (* a z) in y 6.449 * [taylor]: Taking taylor expansion of a in y 6.449 * [backup-simplify]: Simplify a into a 6.449 * [taylor]: Taking taylor expansion of z in y 6.449 * [backup-simplify]: Simplify z into z 6.449 * [backup-simplify]: Simplify (* a z) into (* a z) 6.449 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.449 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.450 * [backup-simplify]: Simplify (/ 1 (- t (* a z))) into (/ 1 (- t (* a z))) 6.450 * [taylor]: Taking taylor expansion of (/ 1 (- t (* a z))) in z 6.450 * [taylor]: Taking taylor expansion of (- t (* a z)) in z 6.450 * [taylor]: Taking taylor expansion of t in z 6.450 * [backup-simplify]: Simplify t into t 6.450 * [taylor]: Taking taylor expansion of (* a z) in z 6.450 * [taylor]: Taking taylor expansion of a in z 6.450 * [backup-simplify]: Simplify a into a 6.450 * [taylor]: Taking taylor expansion of z in z 6.450 * [backup-simplify]: Simplify 0 into 0 6.450 * [backup-simplify]: Simplify 1 into 1 6.450 * [backup-simplify]: Simplify (* a 0) into 0 6.450 * [backup-simplify]: Simplify (- 0) into 0 6.450 * [backup-simplify]: Simplify (+ t 0) into t 6.450 * [backup-simplify]: Simplify (/ 1 t) into (/ 1 t) 6.450 * [taylor]: Taking taylor expansion of (/ 1 t) in t 6.450 * [taylor]: Taking taylor expansion of t in t 6.450 * [backup-simplify]: Simplify 0 into 0 6.450 * [backup-simplify]: Simplify 1 into 1 6.450 * [backup-simplify]: Simplify (/ 1 1) into 1 6.451 * [backup-simplify]: Simplify (- (+ (* 1 (/ 0 1)))) into 0 6.451 * [taylor]: Taking taylor expansion of 0 in a 6.451 * [backup-simplify]: Simplify 0 into 0 6.451 * [backup-simplify]: Simplify 0 into 0 6.451 * [backup-simplify]: Simplify (* -1 (/ z (- t (* a z)))) into (* -1 (/ z (- t (* a z)))) 6.451 * [taylor]: Taking taylor expansion of (* -1 (/ z (- t (* a z)))) in z 6.451 * [taylor]: Taking taylor expansion of -1 in z 6.451 * [backup-simplify]: Simplify -1 into -1 6.451 * [taylor]: Taking taylor expansion of (/ z (- t (* a z))) in z 6.451 * [taylor]: Taking taylor expansion of z in z 6.451 * [backup-simplify]: Simplify 0 into 0 6.451 * [backup-simplify]: Simplify 1 into 1 6.451 * [taylor]: Taking taylor expansion of (- t (* a z)) in z 6.451 * [taylor]: Taking taylor expansion of t in z 6.451 * [backup-simplify]: Simplify t into t 6.451 * [taylor]: Taking taylor expansion of (* a z) in z 6.451 * [taylor]: Taking taylor expansion of a in z 6.451 * [backup-simplify]: Simplify a into a 6.451 * [taylor]: Taking taylor expansion of z in z 6.451 * [backup-simplify]: Simplify 0 into 0 6.451 * [backup-simplify]: Simplify 1 into 1 6.451 * [backup-simplify]: Simplify (* a 0) into 0 6.452 * [backup-simplify]: Simplify (- 0) into 0 6.452 * [backup-simplify]: Simplify (+ t 0) into t 6.452 * [backup-simplify]: Simplify (/ 1 t) into (/ 1 t) 6.452 * [backup-simplify]: Simplify (+ (* z 0) (+ (* 0 0) (* 0 y))) into 0 6.452 * [backup-simplify]: Simplify (- 0) into 0 6.452 * [backup-simplify]: Simplify (+ 0 0) into 0 6.453 * [backup-simplify]: Simplify (+ (* a 0) (+ (* 0 0) (* 0 z))) into 0 6.453 * [backup-simplify]: Simplify (- 0) into 0 6.453 * [backup-simplify]: Simplify (+ 0 0) into 0 6.454 * [backup-simplify]: Simplify (- (/ 0 (- t (* a z))) (+ (* (* -1 (/ (* z y) (- t (* a z)))) (/ 0 (- t (* a z)))) (* (/ 1 (- t (* a z))) (/ 0 (- t (* a z)))))) into 0 6.454 * [taylor]: Taking taylor expansion of 0 in y 6.454 * [backup-simplify]: Simplify 0 into 0 6.454 * [taylor]: Taking taylor expansion of 0 in z 6.454 * [backup-simplify]: Simplify 0 into 0 6.454 * [taylor]: Taking taylor expansion of 0 in t 6.454 * [backup-simplify]: Simplify 0 into 0 6.454 * [taylor]: Taking taylor expansion of 0 in a 6.454 * [backup-simplify]: Simplify 0 into 0 6.454 * [backup-simplify]: Simplify 0 into 0 6.454 * [backup-simplify]: Simplify (+ (* a 0) (* 0 z)) into 0 6.454 * [backup-simplify]: Simplify (- 0) into 0 6.454 * [backup-simplify]: Simplify (+ 0 0) into 0 6.454 * [backup-simplify]: Simplify (- (+ (* (/ 1 (- t (* a z))) (/ 0 (- t (* a z)))))) into 0 6.455 * [taylor]: Taking taylor expansion of 0 in z 6.455 * [backup-simplify]: Simplify 0 into 0 6.455 * [taylor]: Taking taylor expansion of 0 in t 6.455 * [backup-simplify]: Simplify 0 into 0 6.455 * [taylor]: Taking taylor expansion of 0 in a 6.455 * [backup-simplify]: Simplify 0 into 0 6.455 * [backup-simplify]: Simplify 0 into 0 6.455 * [backup-simplify]: Simplify (+ (* z 0) (+ (* 0 1) (* 0 0))) into 0 6.455 * [backup-simplify]: Simplify (+ (* a 0) (* 0 z)) into 0 6.455 * [backup-simplify]: Simplify (- 0) into 0 6.456 * [backup-simplify]: Simplify (+ 0 0) into 0 6.456 * [backup-simplify]: Simplify (- (/ 0 (- t (* a z))) (+ (* (/ z (- t (* a z))) (/ 0 (- t (* a z)))))) into 0 6.456 * [backup-simplify]: Simplify (+ (* -1 0) (* 0 (/ z (- t (* a z))))) into 0 6.456 * [taylor]: Taking taylor expansion of 0 in z 6.456 * [backup-simplify]: Simplify 0 into 0 6.456 * [taylor]: Taking taylor expansion of 0 in t 6.456 * [backup-simplify]: Simplify 0 into 0 6.456 * [taylor]: Taking taylor expansion of 0 in a 6.456 * [backup-simplify]: Simplify 0 into 0 6.456 * [backup-simplify]: Simplify 0 into 0 6.457 * [backup-simplify]: Simplify (+ (* a 1) (* 0 0)) into a 6.457 * [backup-simplify]: Simplify (- a) into (- a) 6.457 * [backup-simplify]: Simplify (+ 0 (- a)) into (- a)