3 Commits

Author	SHA1	Message	Date
Marcin Pawlowski	8cc682aa49	Item 16: the revenue-optimal adversary is not the estimator's worst case ... Both eta ceilings in sec 6.6 come from adversaries optimising something else (revenue, reorg depth), so they bound eta from above without bounding the damage from below. Optimising the estimate directly needs no ratio transform: each transition consumes exactly one block-finding event, so minimising D-hat = (canonical + p_ref * countable uncles)/events is a plain average-reward MDP over the transition table that already carries the orphan counts. One value-iteration pass, no bisection. Unconstrained, the answer degenerates -- and usefully. The optimum is pure abstention: publish nothing, adopt when overtaken, D-hat = 1 - alpha exactly, revenue zero. That is sec 6.4's withholding, which the report already shows is CORRECT measurement rather than mis-measurement, so the unconstrained objective asks the wrong question. The constrained one bites. Sweeping lam * (adversary blocks) - (contribution to D-hat) enumerates policies; the line of interest is where revenue SHARE reaches alpha, i.e. where attacking costs nothing versus mining honestly. At alpha=0.4 such a policy drives D-hat to 0.642 where the revenue-maximiser reaches 0.811 -- 17 points of extra deflation bought with the selfish premium alone. At 0.36 and 0.45 the gaps are 0.082 and 0.103. Below the 1/3 threshold nothing profitable deflates, so the exposure starts exactly where selfish mining does. This revises two claims that were about revenue but read as though they were about the adversary in general: sec 6.7's "the adversary frontier is exactly optimal selfish mining; no compounding lever remains" and sec 8.2's echo of it. Both now say the PROFIT frontier is bounded and the estimator frontier is not the same policy. Note the sweep parameter is deliberately non-monotone in revenue -- selfish mining takes a bigger share of a smaller pie, so raw block rate is maximised by honesty and large lam returns there; it enumerates policies rather than tracing a path. Also closes a fairness loop these findings opened. Sec 6.7(1) credits uncle rewards with compensating orphaned honest producers, computed on the SM1 race where every orphan is a first-fork block. Under a private chain 20-40% of the honest blocks destroyed are unreferenceable by construction, so those producers are uncompensatable at ANY w_u -- not underpaid because p_ref is low, but unreachable because no valid block may name them. The fairness guarantee inherits the same first-fork ceiling as the density repair. Logged as item 19, flagged as a protocol-design question rather than something a schedule fixes. _solve_mdp is refactored into _solve_reward/_greedy_policy/_stationary/ _policy_rates so both objectives share one implementation; optimal_policy_stats reproduces its committed figures exactly (eta 0.4413, D-hat 0.9447/0.8111 at alpha=0.4). 251 tests pass. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>	2026-08-06 14:54:52 +02:00
Marcin Pawlowski	ef82ed614d	Review pass: reproduce every number from its data of record, fix what did not ... Correctness/completeness review of the report and simulator. Verified against the committed parquets: the sec 6.6 countable-ceiling table (cap-64 MDP sweep), sec 6.10 Result 4's depth ceilings, the sec 3.4 uncle-selection table, all adversary-variant numbers, the rho-boundary row-4 quotes (0.976 at rho=0.91, 4-sigma shortfall at 0.96, max cell 1.0024), and the sec 8.4 capstone table. Three defects found, all fixed: 1. The collapse event was not reproducible from the committed script. Study D swept only the default (random) coalition, but the one observed collapse is a whale cell; the "once in 144 runs" count came from an ad-hoc probe. The committed sweep now carries the selection axis (96 runs) and reproduces the event: 1/12 in the whale 50% cell at delta_max = 8, never at 4. All six fold-related passages now quote the committed sweep, which also retires the stale "the full dynamics never reach it" wording in the sec 6 arc, the sec 6.2 intro, row 6 and item 1 -- text that contradicted item 18 since yesterday's finding. 2. capstone.py's printout could not reproduce the report's sec 8.4 table. The report's numbers are a per-replicate-tail aggregation (each replicate burns in against its own early-stop length); the script cut the tail at the ARM's max epoch, silently dropping any replicate that stopped earlier (7 of 8 in the adversary arm) and landing one rounding step off on three cells. The script now aggregates per replicate and prints the SEM; against the existing parquet it reproduces the table exactly (1.001/0.998, 0.342+-0.009 / 0.343+-0.005, p_ref 1.000/0.990, 8 reps both arms). The report table was right all along; sec 6.8's p_ref quote (0.989, the per-arm value) is aligned to 0.990. 3. Small report fixes: slow-beta deflation rounded 0.765 -> "0.77" (now 0.76); fig13's caption now points at the fig36 ceiling instead of implying free recovery; row 5 cites the measured slow-beta standing deflation; the canonical-data paragraph lists the new studies' artifacts; the simulator README's layout block lists the new tests and scripts. Adds a unit test for reorg.countable_recovery_from_depths (the one new function that had none). 236 tests pass; the new-study parquets are copied to the main checkout's runs/, where every other study's data of record lives. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>	2026-08-06 12:29:13 +02:00
Marcin Pawlowski	0510b20684	Countable recovery under a selfish adversary: SM1 hides the first-fork cost ... The countable model can reference only the first block of a fork, so a discarded chain of h honest blocks yields one countable uncle, not h. Sec 6.6 reads the estimator repair off a free knob eta and quotes it at eta = 1 -- attainable under SM1, which acts the moment the honest branch reaches length 1 and so never buries a second block. The optimal SSZ policy waits and does bury them, and there the deployed counting rules cap eta at 0.44 (alpha = 0.4, gamma = 0), landing D-hat at 0.81 rather than the 0.94 an unrestricted count gives -- and the ceiling degrades with alpha while the unrestricted value improves. So SM1 is a faithful proxy for selfish-mining revenue (0.484 vs 0.489) but not for TSI's estimator damage. selfish_mdp: carry per-branch orphan counts on the transition table so the accounting cannot drift from the race logic; optimal_policy_stats solves the policy's stationary distribution for per-event canonical/orphan rates. The per-event rates sum to 1 (every block is canonical or orphaned), which the tests assert as an independent check on the whole derivation. reorg: the same ceiling for the depth-maximising adversary -- 0.52 at alpha = 0.30 with the measured honest fork rate -- reached from the other direction. Neither adversary optimises deflation directly, so both ceilings are upper bounds on eta; that gap is logged as open item 16. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-05 15:29:57 +02:00