defect-survey
Of 1176 exactly correct syntheses, 176 could be built
Every pair of points on a 7×7 grid over the moving body, each pair synthesised into a four-bar and each four-bar verified by the forward solver as reaching all three prescribed poses. 1176 of them do, exactly. Then each is swept from the first pose in both directions, carrying the branch the way a built mechanism must: 810 cannot reach all three without being taken apart and reassembled, and 190 reach them in the wrong order. 176 — 15% — are mechanisms rather than theorems. Nothing in the construction distinguishes them.
Where it is used
- The problem the other way round The problem backwards
- Three positions, and a circumcentre The problem backwards
- Exactly right, and unbuildable Drawn wrongly
- Branches were components all along One path to the tool
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