methodology/hrp@2 vs methodology/hrp@3

Not comparable

1 contract difference prevents these figures from being read against each other.

Where the boundary falls

3 versions, 2 comparability walls

Boundary	Blocking difference
@1 → @2	rebalance frequency 5B -> 21B	why
@2 → @3	weight bound max 1.0 -> 0.25	why

Blocking differences

Field	2	3	Why it matters
weight bound max	1.0	0.25	The earlier version could take positions this one cannot (or vice versa), so the two describe different strategies rather than the same strategy tuned differently.

Differences that do not block

Field	2	3
assumptions	['A 21-business-day rebalance is frequent enough to track...	['A 25% ceiling is binding often enough to diversify without...
assumptions_ref	['assumption/adjusted-close-is-restated@1',...	['assumption/adjusted-close-is-restated@1',...
claims_ref	['claim/hrp-diversifies-without-constraints@1',...	['claim/hrp-outperforms-mvo-out-of-sample@1']
contract	{'universe': ['SPY', 'SH', 'TLT', 'TBT', 'LQD', 'DBC', 'GLD',...	{'universe': ['SPY', 'SH', 'TLT', 'TBT', 'LQD', 'DBC', 'GLD',...
limitations	['Estimated on daily Adj Close, which is restated over time by the...	['Estimated on daily Adj Close, which is restated over time by the...
objective	Allocate across a fixed multi-asset ETF universe using...	Allocate across a fixed multi-asset ETF universe using...
params	{'correlation_distance': {'value': 'sqrt_half_one_minus_rho',...	{'correlation_distance': {'value': 'sqrt_half_one_minus_rho',...
rules	[{'id': 'min_history', 'enforced_by': 'params.lookback',...	[{'id': 'concentration_cap', 'enforced_by':...

These changed without changing what the methodology promises its consumers.

How comparability could be restored

Re-run methodology/hrp@2 under methodology/hrp@3's output contract and compare the re-run against methodology/hrp@3. This is the only route that removes the difference rather than hiding it.
Reporting both figures side by side without a comparability note is the one option that is not available — it is the failure this page exists to prevent.

Performance comparison

Performance comparison unavailable — versions are directly comparable, performance classes are declared, publication permits this surface

✕	Versions are directly comparable	1 blocking contract difference(s)
✕	Performance classes are declared	no performance_class attached
✕	Publication permits this surface	no publication decision recorded
✓	Historical and forward series would be separated

A performance visual is itself a claim. It renders only when every condition holds — otherwise the chart would assert something the artifacts do not support.

Why methodology/hrp@3 exists

Evaluation under protocol/standard@1 flagged hrp@1 and hrp@2 as degenerate: BIL, the cash proxy, took 99.6% of the portfolio on average, effective breadth was 1.01 assets, and the reported Sharpe of 6.59 was cash return divided by cash volatility rather than risk-adjusted performance. This is inherent to HRP, not an implementation error. Recursive bisection allocates inverse-variance, so an instrument with near-zero variance dominates any universe it is in. Lopez de Prado (2016) demonstrates HRP on a universe of comparable-risk assets and does not address a cash proxy. v3 imposes a 25% per-asset ceiling via the output contract, which is the smallest change that makes the allocation describe the methodology rather than describing BIL. The ceiling is applied by the existing apply_bounds step, which iterates clip-and-renormalize to a fixed point. Comparability: this changes weight_bounds in the contract, so results published against v1 and v2 describe a different strategy and must not be linked to v3's.

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