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arxiv: 2604.01201 · v2 · submitted 2026-04-01 · ⚛️ physics.soc-ph · cond-mat.stat-mech

Recognition: 2 theorem links

· Lean Theorem

Message passing and cyclicity transition

Authors on Pith no claims yet

Pith reviewed 2026-05-13 21:31 UTC · model grok-4.3

classification ⚛️ physics.soc-ph cond-mat.stat-mech
keywords message passingpercolationgiant componentcyclesbelief propagationnetwork cyclicitydirected networks
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0 comments X

The pith

Message passing solutions for percolation identify reachability from cycles rather than giant component membership.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper reinterprets the equations of message passing in percolation models. What had been taken as the probability that a node belongs to the giant connected component is shown instead to mark whether that node can be reached from a cycle. The result holds for bond percolation and site percolation alike, and it remains valid on both directed and undirected networks of arbitrary structure. Because the appearance of reachable cycles occurs at a different point from the birth of the giant component, the two transitions are distinct. This separation removes a common source of misapplication when the same equations are used to predict connectivity thresholds.

Core claim

We show that the message passing solutions commonly associated with the probability of belonging to the giant component actually identify reachability from cycles. This interpretation generally applies to bond and site percolation on any directed or undirected networks. Our findings highlight the distinction between transition in cyclicity and the emergence of the giant component.

What carries the argument

The fixed-point solutions of the standard message-passing recursion for percolation, reinterpreted as the indicator of reachability from a cycle.

If this is right

  • The cyclicity transition threshold is generally different from the percolation threshold that produces a giant component.
  • Message passing supplies a direct computational route to the set of nodes from which cycles are reachable.
  • The same equations apply without change to both directed and undirected graphs and to both bond and site percolation.
  • Analyses that previously equated message-passing outputs with giant-component probabilities must be revised.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The reinterpretation suggests that message passing could be repurposed to locate feedback loops in dynamical systems on networks.
  • In directed networks the distinction may separate the onset of recurrent behavior from the onset of long-range reachability.
  • Numerical checks on real-world graphs could reveal how often the two transitions coincide or diverge in practice.

Load-bearing premise

The usual message-passing fixed-point equations remain well-defined and capture exactly the set of nodes reachable from cycles once the percolation process is run.

What would settle it

Compute the message-passing fixed point on a small directed cycle graph with an added dangling edge; the output should mark the cycle nodes as reachable but exclude the dangling node, while the giant-component probability would mark all nodes.

Figures

Figures reproduced from arXiv: 2604.01201 by Takayuki Hiraoka.

Figure 1
Figure 1. Figure 1: FIG. 1. Directed graph [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Mean node marginal (¯y [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Deviation of the message-passing solutions (node [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
read the original abstract

Message passing, also known as belief propagation, is a versatile framework for analyzing models defined on graphs. Its most prototypical application is percolation; yet, the interpretation of the message passing formulation of percolation remains elusive. We show that the message passing solutions commonly associated with the probability of belonging to the giant component actually identify reachability from cycles. This interpretation generally applies to bond and site percolation on any directed or undirected networks. Our findings highlight the distinction between transition in cyclicity and the emergence of the giant component.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 3 minor

Summary. The manuscript reinterprets the standard message-passing (belief propagation) fixed-point equations for percolation on networks. It claims that these solutions, conventionally taken to give the probability that a node belongs to the giant component, instead give the probability of reachability from cycles. The reinterpretation is asserted to hold without additional assumptions for both bond and site percolation on arbitrary directed or undirected graphs, thereby separating the cyclicity transition from giant-component emergence.

Significance. If the central claim is correct, the result would be significant for network science and statistical physics. It supplies a parameter-free reinterpretation of a foundational analytical tool used across percolation, epidemic spreading, and related models, and it applies uniformly to directed and undirected cases. This could resolve interpretive inconsistencies in existing literature and sharpen predictions involving cyclic structure.

minor comments (3)
  1. [Abstract] Abstract: the phrasing 'commonly associated with' could be replaced by a direct reference to the specific fixed-point equations being reinterpreted.
  2. [Section 2] Notation for directed networks (e.g., in the message-update rules) should be introduced with an explicit comparison to the undirected case to avoid ambiguity.
  3. [Figure 1] Figure captions should state the network ensemble and parameter values used for any numerical checks of the cycle-reachability interpretation.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive summary of our work and the recommendation for minor revision. The central claim is that the fixed-point solutions of the standard message-passing equations for percolation identify the probability that a node is reachable from a cycle, rather than the probability that it belongs to the giant component. This reinterpretation requires no additional assumptions and applies uniformly to bond and site percolation on arbitrary directed or undirected networks, thereby separating the cyclicity transition from giant-component emergence.

Circularity Check

0 steps flagged

No significant circularity detected in derivation chain

full rationale

The paper reinterprets the fixed points of standard message-passing equations for bond and site percolation as computing reachability from cycles rather than giant-component membership probabilities. This holds for arbitrary directed or undirected networks and follows directly from the structure of the recursive equations without introducing fitted parameters, self-definitional reductions, or load-bearing self-citations whose validity depends on the present work. No step renames a known empirical pattern as a new result, smuggles an ansatz via prior citation, or imports a uniqueness theorem from overlapping authors; the central claim is a mathematical observation about existing equations and remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract provides no explicit free parameters, axioms, or invented entities; the claim rests on reinterpretation of standard message passing equations.

pith-pipeline@v0.9.0 · 5366 in / 953 out tokens · 32059 ms · 2026-05-13T21:31:45.487716+00:00 · methodology

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Reference graph

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