Skip to content

Auto PrAF routing ignores probabilistic relation-world explosion #2

Description

@ctoth

Problem

At 978b10edb8eaf106f64cd760cfeedce1c3cbb237, PrAF strategy="auto" routes every non-deterministic framework with at most 13 arguments to _compute_exact_enumeration() before it checks _requires_relation_rich_worlds().

That threshold counts only |A|, but the exact implementation enumerates argument subsets and then every probabilistic attack/support configuration. Its stated complexity is O(2^(|A|+|D|)). A small argument set can therefore have an enormous relation-world space.

A route-only probe (with the expensive backends replaced by sentinels) constructs 13 arguments and all 156 directed probabilistic defeats and reports:

arguments=13 probabilistic_defeats=156 route=exact_probe
full-world upper-bound exponent=169

The real exact backend would attempt a worst-case space on the order of 2^169 worlds.

Paper evidence

The repository note papers/Li_2011_ProbabilisticArgumentationFrameworks/notes.md records the paper's exact method as exponential in the number of arguments and defeats (pp. 3-4), with Monte Carlo preferred when exact enumeration becomes impractical (pp. 5, 8). The paper's approximately-13-argument crossover does not justify ignoring uncertain relation count; the recorded experiments used deterministic defeat probabilities.

No page PNGs are present for this paper in the repository, so the page-specific notes are the available local evidence.

Ownership classification

This is a valid generic PrAF route-selection capability in the argumentation.probabilistic owner. It must not be patched in Propstore with a caller-side size heuristic.

Acceptance criteria

  • Auto routing accounts for the number of probabilistic arguments and probabilistic attacks/supports that _compute_exact_enumeration() will enumerate.
  • Relation-rich frameworks are routed away from exact enumeration before the <= 13 arguments shortcut can fire when their world space is not operationally small.
  • Add an executable route-selection contract using a dense small-|A| framework; it must prove the exact backend is not entered without executing the exponential search.
  • Preserve answer-equivalence tests among exact, MC (within its statistical contract), and supported DP routes on tractable fixtures.
  • Keep the mechanism and its telemetry in the generic PrAF owner; do not add a Propstore-specific threshold, wrapper, or fallback.

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions