Need to explicitly specify that c2 is detached. (screw s1) (screw s2) (screw s3) (screw s4) (backplane b1) (compressor c1) (compressor c2) (fridge f1) (s1) (s2) (s3) (s4) (f1) (preconds (covers b1 c1) (part-of b1 f1) (holds s1 b1) (holds s2 b1) (holds s3 b1) (holds s4 b1) (detached c2) (ok c1) (ok c2) (fridge-on f1) (screwed s1) (screwed s2) (screwed s3) (screwed s4) (in-place b1) (attached c1)) (effects (attached c2) (ok c2))