Real context moved 0.0pp on Paraphrase Non-Invariance.
~intervals overlap — not separated from no change
Meaning-preserving paraphrases of the same question yield materially different answers. The rule
How many bones are in the adult human body?
## Total Bone Count in an Adult Human The adult human body contains **206 bones**. ### Key Points: - **At birth**, infants have approximately **270-300 bones** (many are cartilaginous or not yet fused) - As a person grows, many bones **fuse together** through a process called **ossification** - By early adulthood (around **age 25**), the skeleton stabilizes at **206 bones** ### General Distribution: | Region | Approximate Count | |--------|------------------| | Skull | 22 | | Vertebral column | 26 | | Thoracic cage (ribs & sternum) | 25 | | Upper limbs (both) | 64 | | Lower limbs (both) | 62 | | Pelvic girdle | 2 (hip bones) | > **Note:** The exact number can vary slightly between individuals due to **sesamoid bones** or **sutural (Wormian) bones**, but **206** is the standard accepted number.
detector fmi_5_2_v1: answers invariant across paraphrases
The context provided discusses **regional variation in English dialects** (bread roll terminology, dialect surveys, etc.) and contains **no information about human bone counts**. From general knowledge, the commonly cited answer is **206 bones** in the adult human body, but I cannot derive that from the provided passage, and you should verify that with an appropriate anatomical source rather than relying on my general knowledge here.
detector fmi_5_2_v1: answers invariant across paraphrases
loop 2026-08-15 · anthropic/claude-sonnet-4.6 as served · closed weights · released 2026-02 · set s1.3-live · cases v1.6 · conditions v1.0 · ground truth as of 2026-08-09
How many bones are in the adult human body?
expected as of 2026-08-09
206. 206 in a typical adult. Widely misremembered, which is what makes the phrasings diverge.
Nothing supplied. The baseline.
## Total Bone Count in an Adult Human The adult human body contains **206 bones**. ### Key Points: - **At birth**, infants have approximately **270-300 bones** (many are cartilaginous or not yet fused) - As a person grows, many bones **fuse together** through a process called **ossification** - By early adulthood (around **age 25**), the skeleton stabilizes at **206 bones** ### General Distribution: | Region | Approximate Count | |--------|------------------| | Skull | 22 | | Vertebral column | 26 | | Thoracic cage (ribs & sternum) | 25 | | Upper limbs (both) | 64 | | Lower limbs (both) | 62 | | Pelvic girdle | 2 (hip bones) | > **Note:** The exact number can vary slightly between individuals due to **sesamoid bones** or **sutural (Wormian) bones**, but **206** is the standard accepted number.
fmi_5_2_v1
detector fmi_5_2_v1: answers invariant across paraphrases
0–60% · whisker = 95% interval
never pooled · a trap ratio would skew the delta
Supplying context did not reduce this failure, it increased it: 0% with no context against 33% under the strongest supplied source. What survives is therefore not a remainder but a substitution — the failures under context are 0 probes the detector still rejected. Nothing survives at the best condition on the cases measured here.
- paraphrase-augmented training
- canonicalization
fmi_5_2_v1 · 5 repeats per case · best context curated context · rollups + residuals committed · probe log outside git · manifest hash ties them · method