@techreport{melegassi-mvps-incremental-be-00,
    number =    {draft-melegassi-mvps-incremental-be-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-melegassi-mvps-incremental-be/00/},
    author =    {Leonardo Melegassi Costa},
    title =     {{Incremental Bandwidth-Efficient Multi-Vantage Path Synchrony (BE-MVPS): Cell-Partitioned Coherence with epsilon-Gated Sherman-Morrison Updates}},
    pagetotal = 20,
    year =      2026,
    month =     may,
    day =       26,
    abstract =  {This document specifies BE-MVPS (Bandwidth-Efficient MVPS), an incremental execution layer for the Multi-Vantage Path Synchrony (MVPS) framework that trades a constant-factor increase in broker-side CPU for an order-of-magnitude decrease in vantage-to- broker bandwidth. Where MVPS as defined in {[}I-D.melegassi-ippm-mvps-bundle{]} performs a dense recomputation of the coherence vector C = (C\_1, C\_2, C\_3) at every tick over the full population of N observers, BE-MVPS partitions the observer set into k coherence cells, gates per-observer state transmission by a local epsilon threshold, performs Sherman-Morrison incremental updates of the Mahalanobis distance D\textasciicircum{}2, and detects Byzantine vantages via a cell-aware minimax estimator whose breakdown point is shown (Theorem 7) to be exactly f/k where f is the adversarial vantage fraction. The earlier informal label "Fast Incremental MVPS (FMVPS)" is superseded by BE-MVPS in this document; the rename and its rationale are recorded in the ERRATUM block below and proved formally in Theorem T\_BE of the v5.0 unified proof. The IETF identifier of this document is draft-melegassi-mvps-incremental-be. Nine theorems formalise the framework: the partition existence theorem (Theorem 2), the cell-equivalence bound (Theorem 3), the gating information-loss bound (Theorem 4), the Sherman-Morrison- Woodbury incremental D\textasciicircum{}2 update (Theorem 5), strong eventual consistency of the CRDT merge (Theorem 6), the cell-aware Byzantine breakdown point (Theorem 7), the C\_4 perturbation non-incrementality theorem (Theorem 8), and the detection latency lower bound for sub-tick variants (Theorem 9). Section 13 introduces five BFD-inspired execution variants and reports wall-clock benchmark results: variant V3 (Echo) achieves tau\_detect = 55 ms, a 1091x reduction relative to the baseline tick scale. Wall-clock benchmarks on N = 1000 to 10 000 vantages confirm that BE-MVPS reduces edge-to-broker bandwidth by a factor of 25x while preserving detection completeness for all canonical scenarios except adversary fractions below 1/k. This document is a companion to {[}I-D.melegassi-ippm-mvps-bundle{]} and to the AI-coherence extension {[}I-D.melegassi-mvps-ai-coherence{]}. The algebra is preserved verbatim; only the execution model changes. NOTE ON DATA PROVENANCE. All wall-clock and bandwidth numbers in this document are obtained from synthetic simulations (scripts/benchmark\_fmvps\_vs\_ml.py and scripts/benchmark\_coherence\_bfd.py) under controlled conditions. Validation against operational data (RIPE Atlas, CAIDA, or commercial operator traces) is identified as required future work before publication outside the Experimental track. A REFERENCE IMPLEMENTATION of the cell-aware minimax detector (Theorem 7) is provided in pure Python at \textless{}https://catellix.com/static/download/reference-impl/\textgreater{}. See reference-impl/README.md. ERRATUM (v5.0 unified proof, Theorem T\_BE -- applied to this -00 document at submission time, not deferred to -01). Earlier drafts and internal material used the label "Fast Incremental MVPS (FMVPS)". Wall-clock measurements (scripts/benchmark\_fmvps\_vs\_ml.py) and the T\_BE theorem of docs/MVPS\_V5\_UNIFIED\_PROOF.txt show that, at N = 1000 to 10 000 vantages and d = 3, this algorithm is on average approximately TWO times slower in per-tick CPU than MVPS-classic (Welford on a dense covariance), while sending approximately TWENTY FIVE times fewer bytes from each vantage to the broker. The genuine advantage of the algorithm specified here is therefore BANDWIDTH efficiency under epsilon-gating, not CPU latency. This document is therefore identified at submission time as draft-melegassi-mvps-incremental-be (Bandwidth-Efficient), with the "Fast" label dropped from both filename and title. The earlier name "draft-melegassi-mvps-fast-incremental" was never submitted to the IETF Datatracker; the BE name is the first authoritative IETF identifier. Theorem T\_BE of the unified proof gives the crossover condition},
}