Non-Markov Corridor: Memory Windows, Process-Tensor Class, and the Minimal Nonlocal-in-Time Slot
Kenneth Searcy
Abstract
Markov compression can fail even when the present reduced state matches. This paper forces the minimal bookkeeping slot required when state-only (Markov) update laws are not corridor-admissible. We formalize operational Markov failure: corridor-equivalent present reduced states can diverge under a declared future interface (single-time instrument or multi-time strategy), so any state-only update would encode a forbidden tie-break. A conditional finite-depth result follows: whenever bounded past depth suffices at the effective tier, there exists a minimal memory window k>=1 enabling refinement-stable prediction without hidden history tags. In the general adaptive setting, the corridor pressures a multi-time process-tensor / quantum-comb class object: a CP-under-extension, multilinear, coarse-graining-stable, causal/normalized functional on instrument slots. Finally, we show containment: in compressible regimes the multi-time slot reduces (up to corridor equivalence) to CPTP state-only dynamics and, under homogeneity plus generator stabilization, to the Lindblad-class semigroup slot.