0.112 * [progress]: [Phase 1 of 3] Setting up. 0.001 * * * [progress]: [1/2] Preparing points 0.032 * * * [progress]: [2/2] Setting up program. 0.035 * [progress]: [Phase 2 of 3] Improving. 0.035 * [simplify]: Simplifying: (/ (- x (* y z)) (- t (* a z))) 0.035 * * [simplify]: Extracting # 0 : cost 0 0.035 * * [simplify]: Extracting # 1 : cost 0 0.035 * * [simplify]: Extracting # 2 : cost 0 0.035 * * [simplify]: Extracting # 3 : cost 0 0.035 * * [simplify]: Extracting # 4 : cost 0 0.035 * * [simplify]: Extracting # 5 : cost 0 0.035 * * [simplify]: iteration 0 : 10 enodes (cost 11 ) 0.037 * * [simplify]: Extracting # 0 : cost 0 0.037 * * [simplify]: Extracting # 1 : cost 0 0.037 * * [simplify]: Extracting # 2 : cost 0 0.037 * * [simplify]: iteration 1 : 19 enodes (cost 11 ) 0.039 * * [simplify]: Extracting # 0 : cost 0 0.039 * * [simplify]: Extracting # 1 : cost 0 0.039 * * [simplify]: Extracting # 2 : cost 0 0.040 * * [simplify]: iteration 2 : 38 enodes (cost 11 ) 0.045 * * [simplify]: Extracting # 0 : cost 0 0.045 * * [simplify]: Extracting # 1 : cost 0 0.045 * * [simplify]: Extracting # 2 : cost 0 0.045 * * [simplify]: iteration 3 : 52 enodes (cost 11 ) 0.053 * * [simplify]: Extracting # 0 : cost 0 0.054 * * [simplify]: Extracting # 1 : cost 0 0.054 * * [simplify]: Extracting # 2 : cost 0 0.054 * * [simplify]: iteration 4 : 80 enodes (cost 11 ) 0.070 * * [simplify]: Extracting # 0 : cost 0 0.071 * * [simplify]: Extracting # 1 : cost 0 0.071 * * [simplify]: Extracting # 2 : cost 0 0.071 * * [simplify]: iteration 5 : 106 enodes (cost 11 ) 0.126 * * [simplify]: Extracting # 0 : cost 0 0.127 * * [simplify]: Extracting # 1 : cost 0 0.127 * * [simplify]: Extracting # 2 : cost 0 0.127 * * [simplify]: iteration 6 : 150 enodes (cost 11 ) 0.197 * * [simplify]: Extracting # 0 : cost 0 0.198 * * [simplify]: Extracting # 1 : cost 0 0.198 * * [simplify]: Extracting # 2 : cost 0 0.199 * * [simplify]: iteration 7 : 297 enodes (cost 11 ) 0.660 * * [simplify]: Extracting # 0 : cost 0 0.662 * * [simplify]: Extracting # 1 : cost 0 0.664 * * [simplify]: Extracting # 2 : cost 0 0.666 * * [simplify]: iteration 8 : 1079 enodes (cost 11 ) 6.370 * * [simplify]: Extracting # 0 : cost 0 6.388 * * [simplify]: Extracting # 1 : cost 0 6.396 * * [simplify]: Extracting # 2 : cost 0 6.403 * * [simplify]: Extracting # 3 : cost 0 6.410 * * [simplify]: Extracting # 4 : cost 0 6.417 * * [simplify]: iteration done: 5000 enodes (cost 11 ) 6.417 * [simplify]: Simplified to: (/ (- x (* y z)) (- t (* a z))) 6.418 * * [progress]: iteration 1 / 4 6.418 * * * [progress]: picking best candidate 6.422 * * * * [pick]: Picked # 6.422 * * * [progress]: localizing error 6.439 * * * [progress]: generating rewritten candidates 6.439 * * * * [progress]: [ 1 / 2 ] rewriting at (2) 6.462 * * * * [progress]: [ 2 / 2 ] rewriting at (2 1) 6.469 * * * [progress]: generating series expansions 6.469 * * * * [progress]: [ 1 / 2 ] generating series at (2) 6.469 * [backup-simplify]: Simplify (/ (- x (* y z)) (- t (* a z))) into (/ (- x (* z y)) (- t (* a z))) 6.469 * [approximate]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in (x y z t a) around 0 6.469 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in a 6.469 * [taylor]: Taking taylor expansion of (- x (* z y)) in a 6.469 * [taylor]: Taking taylor expansion of x in a 6.469 * [backup-simplify]: Simplify x into x 6.469 * [taylor]: Taking taylor expansion of (* z y) in a 6.469 * [taylor]: Taking taylor expansion of z in a 6.469 * [backup-simplify]: Simplify z into z 6.469 * [taylor]: Taking taylor expansion of y in a 6.470 * [backup-simplify]: Simplify y into y 6.470 * [taylor]: Taking taylor expansion of (- t (* a z)) in a 6.470 * [taylor]: Taking taylor expansion of t in a 6.470 * [backup-simplify]: Simplify t into t 6.470 * [taylor]: Taking taylor expansion of (* a z) in a 6.470 * [taylor]: Taking taylor expansion of a in a 6.470 * [backup-simplify]: Simplify 0 into 0 6.470 * [backup-simplify]: Simplify 1 into 1 6.470 * [taylor]: Taking taylor expansion of z in a 6.470 * [backup-simplify]: Simplify z into z 6.470 * [backup-simplify]: Simplify (* z y) into (* z y) 6.470 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.470 * [backup-simplify]: Simplify (+ x (- (* z y))) into (- x (* z y)) 6.470 * [backup-simplify]: Simplify (* 0 z) into 0 6.471 * [backup-simplify]: Simplify (- 0) into 0 6.471 * [backup-simplify]: Simplify (+ t 0) into t 6.471 * [backup-simplify]: Simplify (/ (- x (* z y)) t) into (/ (- x (* z y)) t) 6.471 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in t 6.471 * [taylor]: Taking taylor expansion of (- x (* z y)) in t 6.471 * [taylor]: Taking taylor expansion of x in t 6.471 * [backup-simplify]: Simplify x into x 6.471 * [taylor]: Taking taylor expansion of (* z y) in t 6.471 * [taylor]: Taking taylor expansion of z in t 6.471 * [backup-simplify]: Simplify z into z 6.471 * [taylor]: Taking taylor expansion of y in t 6.471 * [backup-simplify]: Simplify y into y 6.471 * [taylor]: Taking taylor expansion of (- t (* a z)) in t 6.471 * [taylor]: Taking taylor expansion of t in t 6.471 * [backup-simplify]: Simplify 0 into 0 6.471 * [backup-simplify]: Simplify 1 into 1 6.471 * [taylor]: Taking taylor expansion of (* a z) in t 6.471 * [taylor]: Taking taylor expansion of a in t 6.471 * [backup-simplify]: Simplify a into a 6.471 * [taylor]: Taking taylor expansion of z in t 6.471 * [backup-simplify]: Simplify z into z 6.471 * [backup-simplify]: Simplify (* z y) into (* z y) 6.472 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.472 * [backup-simplify]: Simplify (+ x (- (* z y))) into (- x (* z y)) 6.472 * [backup-simplify]: Simplify (* a z) into (* a z) 6.472 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.472 * [backup-simplify]: Simplify (+ 0 (- (* a z))) into (- (* a z)) 6.472 * [backup-simplify]: Simplify (/ (- x (* z y)) (- (* a z))) into (* -1 (/ (- x (* z y)) (* a z))) 6.472 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in z 6.472 * [taylor]: Taking taylor expansion of (- x (* z y)) in z 6.472 * [taylor]: Taking taylor expansion of x in z 6.472 * [backup-simplify]: Simplify x into x 6.472 * [taylor]: Taking taylor expansion of (* z y) in z 6.472 * [taylor]: Taking taylor expansion of z in z 6.472 * [backup-simplify]: Simplify 0 into 0 6.472 * [backup-simplify]: Simplify 1 into 1 6.472 * [taylor]: Taking taylor expansion of y in z 6.472 * [backup-simplify]: Simplify y into y 6.472 * [taylor]: Taking taylor expansion of (- t (* a z)) in z 6.472 * [taylor]: Taking taylor expansion of t in z 6.472 * [backup-simplify]: Simplify t into t 6.472 * [taylor]: Taking taylor expansion of (* a z) in z 6.473 * [taylor]: Taking taylor expansion of a in z 6.473 * [backup-simplify]: Simplify a into a 6.473 * [taylor]: Taking taylor expansion of z in z 6.473 * [backup-simplify]: Simplify 0 into 0 6.473 * [backup-simplify]: Simplify 1 into 1 6.473 * [backup-simplify]: Simplify (* 0 y) into 0 6.473 * [backup-simplify]: Simplify (- 0) into 0 6.473 * [backup-simplify]: Simplify (+ x 0) into x 6.473 * [backup-simplify]: Simplify (* a 0) into 0 6.474 * [backup-simplify]: Simplify (- 0) into 0 6.474 * [backup-simplify]: Simplify (+ t 0) into t 6.474 * [backup-simplify]: Simplify (/ x t) into (/ x t) 6.474 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in y 6.474 * [taylor]: Taking taylor expansion of (- x (* z y)) in y 6.474 * [taylor]: Taking taylor expansion of x in y 6.474 * [backup-simplify]: Simplify x into x 6.474 * [taylor]: Taking taylor expansion of (* z y) in y 6.474 * [taylor]: Taking taylor expansion of z in y 6.474 * [backup-simplify]: Simplify z into z 6.474 * [taylor]: Taking taylor expansion of y in y 6.474 * [backup-simplify]: Simplify 0 into 0 6.474 * [backup-simplify]: Simplify 1 into 1 6.474 * [taylor]: Taking taylor expansion of (- t (* a z)) in y 6.474 * [taylor]: Taking taylor expansion of t in y 6.474 * [backup-simplify]: Simplify t into t 6.474 * [taylor]: Taking taylor expansion of (* a z) in y 6.474 * [taylor]: Taking taylor expansion of a in y 6.474 * [backup-simplify]: Simplify a into a 6.474 * [taylor]: Taking taylor expansion of z in y 6.474 * [backup-simplify]: Simplify z into z 6.474 * [backup-simplify]: Simplify (* z 0) into 0 6.475 * [backup-simplify]: Simplify (- 0) into 0 6.475 * [backup-simplify]: Simplify (+ x 0) into x 6.475 * [backup-simplify]: Simplify (* a z) into (* a z) 6.475 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.475 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.475 * [backup-simplify]: Simplify (/ x (- t (* a z))) into (/ x (- t (* a z))) 6.475 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in x 6.475 * [taylor]: Taking taylor expansion of (- x (* z y)) in x 6.475 * [taylor]: Taking taylor expansion of x in x 6.475 * [backup-simplify]: Simplify 0 into 0 6.475 * [backup-simplify]: Simplify 1 into 1 6.475 * [taylor]: Taking taylor expansion of (* z y) in x 6.475 * [taylor]: Taking taylor expansion of z in x 6.475 * [backup-simplify]: Simplify z into z 6.475 * [taylor]: Taking taylor expansion of y in x 6.475 * [backup-simplify]: Simplify y into y 6.475 * [taylor]: Taking taylor expansion of (- t (* a z)) in x 6.475 * [taylor]: Taking taylor expansion of t in x 6.475 * [backup-simplify]: Simplify t into t 6.475 * [taylor]: Taking taylor expansion of (* a z) in x 6.475 * [taylor]: Taking taylor expansion of a in x 6.475 * [backup-simplify]: Simplify a into a 6.475 * [taylor]: Taking taylor expansion of z in x 6.475 * [backup-simplify]: Simplify z into z 6.476 * [backup-simplify]: Simplify (* z y) into (* z y) 6.476 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.476 * [backup-simplify]: Simplify (+ 0 (- (* z y))) into (- (* z y)) 6.476 * [backup-simplify]: Simplify (* a z) into (* a z) 6.476 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.476 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.476 * [backup-simplify]: Simplify (/ (- (* z y)) (- t (* a z))) into (* -1 (/ (* z y) (- t (* a z)))) 6.476 * [taylor]: Taking taylor expansion of (/ (- x (* z y)) (- t (* a z))) in x 6.476 * [taylor]: Taking taylor expansion of (- x (* z y)) in x 6.476 * [taylor]: Taking taylor expansion of x in x 6.476 * [backup-simplify]: Simplify 0 into 0 6.476 * [backup-simplify]: Simplify 1 into 1 6.476 * [taylor]: Taking taylor expansion of (* z y) in x 6.476 * [taylor]: Taking taylor expansion of z in x 6.476 * [backup-simplify]: Simplify z into z 6.476 * [taylor]: Taking taylor expansion of y in x 6.476 * [backup-simplify]: Simplify y into y 6.476 * [taylor]: Taking taylor expansion of (- t (* a z)) in x 6.477 * [taylor]: Taking taylor expansion of t in x 6.477 * [backup-simplify]: Simplify t into t 6.477 * [taylor]: Taking taylor expansion of (* a z) in x 6.477 * [taylor]: Taking taylor expansion of a in x 6.477 * [backup-simplify]: Simplify a into a 6.477 * [taylor]: Taking taylor expansion of z in x 6.477 * [backup-simplify]: Simplify z into z 6.477 * [backup-simplify]: Simplify (* z y) into (* z y) 6.477 * [backup-simplify]: Simplify (- (* z y)) into (- (* z y)) 6.477 * [backup-simplify]: Simplify (+ 0 (- (* z y))) into (- (* z y)) 6.477 * [backup-simplify]: Simplify (* a z) into (* a z) 6.477 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.477 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.477 * [backup-simplify]: Simplify (/ (- (* z y)) (- t (* a z))) into (* -1 (/ (* z y) (- t (* a z)))) 6.478 * [taylor]: Taking taylor expansion of (* -1 (/ (* z y) (- t (* a z)))) in y 6.478 * [taylor]: Taking taylor expansion of -1 in y 6.478 * [backup-simplify]: Simplify -1 into -1 6.478 * [taylor]: Taking taylor expansion of (/ (* z y) (- t (* a z))) in y 6.478 * [taylor]: Taking taylor expansion of (* z y) in y 6.478 * [taylor]: Taking taylor expansion of z in y 6.478 * [backup-simplify]: Simplify z into z 6.478 * [taylor]: Taking taylor expansion of y in y 6.478 * [backup-simplify]: Simplify 0 into 0 6.478 * [backup-simplify]: Simplify 1 into 1 6.478 * [taylor]: Taking taylor expansion of (- t (* a z)) in y 6.478 * [taylor]: Taking taylor expansion of t in y 6.478 * [backup-simplify]: Simplify t into t 6.478 * [taylor]: Taking taylor expansion of (* a z) in y 6.478 * [taylor]: Taking taylor expansion of a in y 6.478 * [backup-simplify]: Simplify a into a 6.478 * [taylor]: Taking taylor expansion of z in y 6.478 * [backup-simplify]: Simplify z into z 6.478 * [backup-simplify]: Simplify (* z 0) into 0 6.479 * [backup-simplify]: Simplify (+ (* z 1) (* 0 0)) into z 6.479 * [backup-simplify]: Simplify (* a z) into (* a z) 6.479 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.479 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.479 * [backup-simplify]: Simplify (/ z (- t (* a z))) into (/ z (- t (* a z))) 6.480 * [backup-simplify]: Simplify (+ (* z 0) (* 0 y)) into 0 6.480 * [backup-simplify]: Simplify (- 0) into 0 6.481 * [backup-simplify]: Simplify (+ 1 0) into 1 6.481 * [backup-simplify]: Simplify (+ (* a 0) (* 0 z)) into 0 6.481 * [backup-simplify]: Simplify (- 0) into 0 6.482 * [backup-simplify]: Simplify (+ 0 0) into 0 6.482 * [backup-simplify]: Simplify (- (/ 1 (- t (* a z))) (+ (* (* -1 (/ (* z y) (- t (* a z)))) (/ 0 (- t (* a z)))))) into (/ 1 (- t (* a z))) 6.482 * [taylor]: Taking taylor expansion of (/ 1 (- t (* a z))) in y 6.482 * [taylor]: Taking taylor expansion of (- t (* a z)) in y 6.482 * [taylor]: Taking taylor expansion of t in y 6.482 * [backup-simplify]: Simplify t into t 6.482 * [taylor]: Taking taylor expansion of (* a z) in y 6.482 * [taylor]: Taking taylor expansion of a in y 6.482 * [backup-simplify]: Simplify a into a 6.482 * [taylor]: Taking taylor expansion of z in y 6.482 * [backup-simplify]: Simplify z into z 6.482 * [backup-simplify]: Simplify (* a z) into (* a z) 6.482 * [backup-simplify]: Simplify (- (* a z)) into (- (* a z)) 6.483 * [backup-simplify]: Simplify (+ t (- (* a z))) into (- t (* a z)) 6.483 * [backup-simplify]: Simplify (/ 1 (- t (* a z))) into (/ 1 (- t (* a z))) 6.483 * [taylor]: Taking taylor expansion of (/ 1 (- t (* a z))) in z 6.483 * [taylor]: Taking taylor expansion of (- t (* a z)) in z 6.483 * [taylor]: Taking taylor expansion of t in z 6.483 * [backup-simplify]: Simplify t into t 6.483 * [taylor]: Taking taylor expansion of (* a z) in z 6.483 * [taylor]: Taking taylor expansion of a in z 6.483 * [backup-simplify]: Simplify a into a 6.483 * [taylor]: Taking taylor expansion of z in z 6.483 * [backup-simplify]: Simplify 0 into 0 6.483 * [backup-simplify]: Simplify 1 into 1 6.483 * [backup-simplify]: Simplify (* a 0) into 0 6.483 * [backup-simplify]: Simplify (- 0) into 0 6.483 * [backup-simplify]: Simplify (+ t 0) into t 6.484 * [backup-simplify]: Simplify (/ 1 t) into (/ 1 t) 6.484 * [taylor]: Taking taylor expansion of (/ 1 t) in t 6.484 * [taylor]: Taking taylor expansion of t in t 6.484 * [backup-simplify]: Simplify 0 into 0 6.484 * [backup-simplify]: Simplify 1 into 1 6.484 * [backup-simplify]: Simplify (/ 1 1) into 1 6.485 * [backup-simplify]: Simplify (- (+ (* 1 (/ 0 1)))) into 0 6.485 * [taylor]: Taking taylor expansion of 0 in a 6.485 * [backup-simplify]: Simplify 0 into 0 6.485 * [backup-simplify]: Simplify 0 into 0 6.485 * [backup-simplify]: Simplify (* -1 (/ z (- t (* a z)))) into (* -1 (/ z (- t (* a z)))) 6.485 * [taylor]: Taking taylor expansion of (* -1 (/ z (- t (* a z)))) in z 6.485 * [taylor]: Taking taylor expansion of -1 in z 6.485 * [backup-simplify]: Simplify -1 into -1 6.485 * [taylor]: Taking taylor expansion of (/ z (- t (* a z))) in z 6.485 * [taylor]: Taking taylor expansion of z in z 6.485 * [backup-simplify]: Simplify 0 into 0 6.485 * [backup-simplify]: Simplify 1 into 1 6.485 * [taylor]: Taking taylor expansion of (- t (* a z)) in z 6.485 * [taylor]: Taking taylor expansion of t in z 6.485 * [backup-simplify]: Simplify t into t 6.485 * [taylor]: Taking taylor expansion of (* a z) in z 6.485 * [taylor]: Taking taylor expansion of a in z 6.485 * [backup-simplify]: Simplify a into a 6.485 * [taylor]: Taking taylor expansion of z in z 6.485 * [backup-simplify]: Simplify 0 into 0 6.485 * [backup-simplify]: Simplify 1 into 1 6.486 * [backup-simplify]: Simplify (* a 0) into 0 6.486 * [backup-simplify]: Simplify (- 0) into 0 6.486 * [backup-simplify]: Simplify (+ t 0) into t 6.486 * [backup-simplify]: Simplify (/ 1 t) into (/ 1 t) 6.487 * [backup-simplify]: Simplify (+ (* z 0) (+ (* 0 0) (* 0 y))) into 0 6.487 * [backup-simplify]: Simplify (- 0) into 0 6.487 * [backup-simplify]: Simplify (+ 0 0) into 0 6.488 * [backup-simplify]: Simplify (+ (* a 0) (+ (* 0 0) (* 0 z))) into 0 6.488 * [backup-simplify]: Simplify (- 0) into 0 6.488 * [backup-simplify]: Simplify (+ 0 0) into 0 6.489 * [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 6.489 * [taylor]: Taking taylor expansion of 0 in y 6.489 * [backup-simplify]: Simplify 0 into 0 6.489 * [taylor]: Taking taylor expansion of 0 in z 6.489 * [backup-simplify]: Simplify 0 into 0 6.489 * [taylor]: Taking taylor expansion of 0 in t 6.489 * [backup-simplify]: Simplify 0 into 0 6.489 * [taylor]: Taking taylor expansion of 0 in a 6.489 * [backup-simplify]: Simplify 0 into 0 6.489 * [backup-simplify]: Simplify 0 into 0 6.489 * [backup-simplify]: Simplify (+ (* a 0) (* 0 z)) into 0 6.490 * [backup-simplify]: Simplify (- 0) into 0 6.490 * [backup-simplify]: Simplify (+ 0 0) into 0 6.491 * [backup-simplify]: Simplify (- (+ (* (/ 1 (- t (* a z))) (/ 0 (- t (* a z)))))) into 0 6.491 * [taylor]: Taking taylor expansion of 0 in z 6.491 * [backup-simplify]: Simplify 0 into 0 6.491 * [taylor]: Taking taylor expansion of 0 in t 6.491 * [backup-simplify]: Simplify 0 into 0 6.491 * [taylor]: Taking taylor expansion of 0 in a 6.491 * [backup-simplify]: Simplify 0 into 0 6.491 * [backup-simplify]: Simplify 0 into 0 6.491 * [backup-simplify]: Simplify (+ (* z 0) (+ (* 0 1) (* 0 0))) into 0 6.492 * [backup-simplify]: Simplify (+ (* a 0) (* 0 z)) into 0 6.492 * [backup-simplify]: Simplify (- 0) into 0 6.492 * [backup-simplify]: Simplify (+ 0 0) into 0 6.493 * [backup-simplify]: Simplify (- (/ 0 (- t (* a z))) (+ (* (/ z (- t (* a z))) (/ 0 (- t (* a z)))))) into 0 6.493 * [backup-simplify]: Simplify (+ (* -1 0) (* 0 (/ z (- t (* a z))))) into 0 6.493 * [taylor]: Taking taylor expansion of 0 in z 6.493 * [backup-simplify]: Simplify 0 into 0 6.493 * [taylor]: Taking taylor expansion of 0 in t 6.493 * [backup-simplify]: Simplify 0 into 0 6.493 * [taylor]: Taking taylor expansion of 0 in a 6.493 * [backup-simplify]: Simplify 0 into 0 6.493 * [backup-simplify]: Simplify 0 into 0 6.494 * [backup-simplify]: Simplify (+ (* a 1) (* 0 0)) into a 6.494 * [backup-simplify]: Simplify (- a) into (- a) 6.494 * [backup-simplify]: Simplify (+ 0 (- a)) into (- a)