A knowledge-level approach for effective acting, sensing, and planning
Bibliographic record
Abstract
In this thesis we investigate a "knowledge-level" approach to the problem of modelling an agent's incomplete knowledge, for the purpose of planning or high-level agent control. We investigate two formal accounts of knowledge, action, and sensing in the situation calculus: the Scherl and Levesque ( SL) approach that is based on "possible worlds," and the Demolombe and Pozos Parra (DP) approach that utilizes a set of "knowledge fluents." While the SL approach is expressive, reasoning is computationally more expensive; the DP account treats knowledge change as ordinary fluent change, but restricts its representation to primitive knowledge-level assertions. To relate these two accounts we construct "combined action theories," and prove that a set of primitive knowledge assertions remains identical in both accounts after any sequence of actions. We also extend this equivalence to more complex formulae. These results allow us to compile an expressive class of SL theories into equivalent DP theories that avoid the computational drawbacks of possible world reasoning. Moreover, this correspondence gives us a correctness result for the DP treatment of knowledge and action, in terms of possible worlds. We also describe a new conditional planner called PKS (Planning with Knowledge and Sensing), that works directly at the knowledge level to construct plans with incomplete information and sensing actions. PKS represents it knowledge by using a collection of databases, each of which models a particular type of knowledge. The contents of each database have a fixed, formal translation to a modal logic of knowledge that defines the planner's knowledge state. Actions are modelled as updates to the databases (i.e., the knowledge state), rather than the world state, which differs from other planners. This representation supports features, like functions, that world-level planners often have difficulty working with. We also describe a preliminary procedure for automatically converting DP actions into PKS actions. Together with our SL equivalence results, this transformation provides an important first step towards the goal of compiling world-level actions into equivalent knowledge-level actions usable by PKS. Finally, we demonstrate PKS's expressiveness and efficiency with a series of planning problems that also illustrate the potential of the knowledge-based approach.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.013 |
| Scholarly communication | 0.007 | 0.014 |
| Open science | 0.004 | 0.006 |
| Research integrity | 0.002 | 0.005 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".