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I had planned to flip uncle_window_anchor's default to "parent" so new configs would measure the proposed design by default. Tried it, and it breaks a documented guarantee: key() appends the anchor only when it is not "uncle", so with "parent" as the default an --old run's key is no longer byte-identical to the pre-redesign key and --old stops bit-reproducing historical runs (sec 9). o.key() == o._base_key() fails outright. Reverted, and on reflection the default was wrong for a second reason anyway. The report's job is to describe the protocol as deployed and to RECOMMEND changes; the default should therefore be the deployed rule, with the proposal as an explicit arm. That is exactly the convention fixed_point already follows (default exact f = the analysis convention, explicit True = spec-faithful). Both reasons are recorded on the field. To make the distinction visible rather than implicit, the spec-as-is studies now pin uncle_window_anchor: uncle explicitly -- spec_point.py, spec_jitter.py and the three spec-point-*.yaml configs answer "what does the DEPLOYED chain do", so they must not drift onto a proposal if a default ever moves. Adds uncle_window_anchor as a sweep axis (SweepConfig field plus _SWEEP_AXES), and configs/absorption-window-anchor.yaml: the sec 3.4 absorption sweep re-run under both anchors at three delays. That study is the one that can move a recommendation -- the W >= 7/f floor was measured against the uncle gap, and the parent gap runs about one block-interval longer, so the floor should sit higher and the margin behind W = 10/f shrink. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
49 lines
3.6 KiB
YAML
49 lines
3.6 KiB
YAML
# The diagnostic: does per-recipient delay variance reproduce the standalone result?
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#
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# The one experiment here that could invalidate the REPORT rather than the spec section it is
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# checking. The hypothesis for the discrepancy is modelling, not measurement: the
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# standalone simulation drew an INDEPENDENT propagation delay per (block, recipient), while this
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# simulator's blend topology runs a cascade of relays and then floods network-wide from the LAST
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# relay, so nodes receive a block at nearly the same time and their views stay synchronised.
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# Independent per-recipient draws maximise view divergence, which is exactly what manufactures the
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# depth->=2 forks the first-fork rule cannot recover.
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#
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# jitter_mean adds per-(block, node) arrival noise on top of the cascade, so sweeping it
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# interpolates between the two models: 0 is the report's cascade, large values approach the
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# standalone's independent-delay regime. The observable that decides it is deep_orphan_share --
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# the fraction of in-window orphans sitting deeper than the first block of their fork, which is
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# precisely the structural quantity behind the spec section's deep-fork claim.
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#
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# This is also the report's open item 15 (correlated/heterogeneous latency untested).
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#
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# EXACT ORACLE REQUIRED: the windowed fork choice and the arrival prune are only bit-exact at
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# jitter_mean == 0 (a jittered arrival can cross the deterministic horizon), so both are off. That
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# forces the full (N x n_blocks) matrix and makes each run ~17 s at k = 2160.
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#
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# Run TWICE — default (countable) and with --old. `--old` is NOT a candidate design: under the
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# current spec a block carrying a deep-fork reference is REJECTED, so it is an unreachable upper
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# bound on what any counting rule could recover, and the countable-vs-ceiling gap is the
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# first-fork cost. Latency is in SLOTS (1 slot = 1 s).
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n_nodes: [1000] # network size
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stake_dist: [pareto] # heavy-tailed (realistic) stake distribution
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topology: [blend] # Blend mixnet — the deployment transport
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degree: [6] # peering degree of the d-regular graph
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link_latency_mean: [0.5] # natural geographic transport (sub-slot)
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link_latency_dist: [geo] # real-world geographic band mixture
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blend_hops: [3] # the spec's Blend cascade length
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blend_delay_max: [4.0] # the spec's operating point (rho ~ 0.27)
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max_uncles: [0, 1, 2, 4] # 0 = negative control; 4 = the spec's MAX_UNCLES
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uncle_strategy: [oldest] # spec Uncle Selection
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uncle_window_anchor: [uncle] # SPEC AS DEPLOYED, not the sec 6.12 proposal
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init_dest: [common] # per-node initial D_est from agreement
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replicates: 12 # exact-oracle runs are ~17 s each; 12 x 40 cells
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base: # per-run settings shared by every cell
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k: 2160 # true security parameter
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epochs: 20 # equilibrium within ~2 epochs; burn 50%
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f: 0.03333333333333333 # slot activation coefficient (1/30)
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genesis_d_factor: 0.5 # start near true stake (cheap epoch 0)
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early_stop: true
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windowed_fork_choice: false # exact oracle: required once jitter > 0
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prune_arrival: false # ...and the prune needs the same horizon
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jitter_mean: 0.0 # OVERRIDDEN per run by scripts/spec_jitter.py
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