PhD Dissertation Defense

University of South Carolina

Generalized Planning Using Language Models and Its Applications

Vishal Pallagani

PhD in Computer Science, University of South Carolina

Five research questions Language models and planning Neuro-symbolic AI

Dissertation Overview

Overview

A dissertation-scale summary of the problem formulation, architectural choices, and empirical findings.

The central claim of the dissertation is that language-model-based planning should be formulated as a constrained computational problem over explicit symbolic structure rather than as unconstrained autoregressive text generation.

Accordingly, the work combines taxonomy construction, controlled benchmarking, state-centric prediction, graph-based representations, symbolic successor validation, and metacognitive routing to identify where learned components are beneficial and where algorithmic structure is necessary.

Problem setting Generalized planning is treated as reasoning over state transitions, validity constraints, and transfer beyond the training distribution.
Architectural principle Language models act as proposers, predictors, or representational components, while symbolic modules provide verification, repair, search, and execution semantics.

Technical TL;DR

Problem formulation Standalone language-model generation lacks guarantees on plan validity, executability, and systematic generalization across planning domains.
Systems thesis More reliable performance emerges when learned components are embedded inside structured planning pipelines with explicit states, constrained decoding, symbolic verification, and recovery mechanisms.
Methodological contribution The dissertation moves from descriptive analysis to constructive model and architecture design, then evaluates those designs in both benchmark and application settings.
Overall conclusion Hybrid neuro-symbolic planning architectures are more dependable than pure generation pipelines when correctness, robustness, and domain transfer are first-class requirements.

Research Arc

1
Characterization

Construct a taxonomy of functional language-model roles in planning and analyze category drift across the literature.

2
Specialization

Evaluate valid plan generation and characterize the limitations of prompting and fine-tuning under distribution shift.

3
State-centric modeling

Replace action-sequence generation with successor-state prediction and symbolic successor selection.

4
Neuro-symbolic integration

Integrate learned proposers with symbolic verification, repair, and metacognitive control.

5
Applications

Evaluate the resulting methods in dialog systems, trustworthy assistance, and adaptive manufacturing.

Committee

Committee Members

Major Professor

Biplav Srivastava

University of South Carolina

University of South Carolina

Major Professor

Amit Sheth

University of South Carolina

University of South Carolina

Examination Chair

Ramtin Zand

University of South Carolina

University of South Carolina

Committee Member

Lior Horesh

IBM Research

IBM Research

Committee Member

Sarath Sreedharan

Colorado State University

Colorado State University