Which data structures do Facade's beat sequencer, the Automated Story Director's narrative-mediation tree and Versu's social practices use to hold story state and authorial control, and what did each paper evaluate?

Three primary papers give three reusable structures. Facade (Mateas and Stern 2005) annotates each beat with preconditions, weights, priorities and tension effects, and picks the unused eligible beat closest to an authored tension arc. The Automated Story Director (Riedl and Stern 2006) holds the story as a partially ordered plan with causal links, precomputes a tree of contingency plans for every player action that threatens a link, and reported a prototype whose tree had over 1000 paths. Versu (Evans and Short 2014) gives characters strong autonomy, uses social practices as suggestion-only joint plans, and makes each episode's story manager a reactive practice. None reports a controlled comparison against alternatives. Curator qualifications: ASD: 'The Automated Story Director generates a tree of contingency plans with over 1000 paths, although most are minor variations for maintaining narrative coherence'; 'relatively few user actions threaten the plot. This allows for a larger repertoire of user actions'. Excerpts E3, E4, E8 found verbatim (C3R-0016 batch check). Facade text: 'local agency' 8, 'global agency' 8. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://cdn.aaai.org/ojs/18722/18722-52-22361-1-10-20210928.pdf",
      "note": "Riedl & Stern TIDSE 2006 PDF"
    },
    {
      "url": "https://faculty.cc.gatech.edu/~riedl/pubs/tidse06a.pdf",
      "note": "Riedl & Stern TIDSE 2006 PDF"
    },
    {
      "url": "https://www.cs.uky.edu/~sgware/reading/papers/roberts2008survey.pdf",
      "note": "Riedl & Stern TIDSE 2006 PDF"
    },
    {
      "url": "https://cs.uky.edu/~sgware/reading/papers/evans2014versu.pdf",
      "note": "Riedl & Stern TIDSE 2006 PDF"
    }
  ]
}