Library · Machine learning & AI

What Rule-Based & Expert Systems got wrong, from 29 theses

Summary written by a model from the records below: The records demonstrate that rule-based and expert systems frequently struggle when dealing with dynamic environments, complex linguistic variability, and noisy human behavioral data. Across numerous tasks, handcrafted heuristics and rigid deterministic thresholds underperformed probabilistic models, learned representations, and standard statistical baselines. These records come from graduate theses, 2021 to 2026, each labeled with its degree where the repository states it, and each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.

29
theses
16
institutions
29
failure records
5
failure modes

Plus 3 problems the authors left open, listed at the end.

Failure modes, by theses reporting them

Select a mode to jump to its records.

Rule-based and heuristic natural language processing fails to handle complex linguistic variation
8
8 theses · 8 institutions · 8 records
Rule-based deduction engines and heuristic abstractions lack adaptability and learning capacity
6
6 theses · 5 institutions · 6 records
Rigid mathematical thresholds and deterministic rules fail in dynamic or continuous environments
5
5 theses · 5 institutions · 5 records
Deterministic heuristics fail to capture uncertainty and stochasticity in human behavior
6
6 theses · 4 institutions · 6 records
Rule-based classifiers and heuristic feature selectors underperform probabilistic and learned baselines
4
4 theses · 4 institutions · 4 records

Rule-based and heuristic natural language processing fails to handle complex linguistic variation

8 theses · 8 institutions

Handcrafted syntactic patterns, regular expressions, and grammatical rules frequently break down when faced with complex negation, layout variations, and idiosyncratic semantic shifts. Consequently, these rigid text processing approaches yield low precision and poor recall compared to learned models, or distort underlying sentence semantics during data manipulation.

Tried and failed

rule-based natural language processing applied to clinical report diagnosis extraction. Reason: failed to correctly handle complex clinical negation, causing poor specificity and low F1 score

Artificial intelligence applications for the acquisition, analysis and reporting of cardiovascular magnetic resonance imaging · Imperial · PhD

Tried and failed

rule-based pattern matching NLP applied to inter-parameter dependency extraction from documentation. Outcome: no signal. Reason: rigid syntactic patterns failed to match diverse real-world natural language documentation structures

Effective Automation of Black-Box Testing for REST APIs with Machine Learning and Language Models · Georgia Tech · PhD

Tried and failed

rule-based text data augmentation applied to intent classification. Outcome: worse than baseline. Reason: heuristic word-level perturbations alter sentence semantics and label alignment

Lifelong Machine Learning with Data Efficiency and Knowledge Retention · EPFL · PhD

Tried and failed

rule-based compositional semantics and derivational morphology applied to compound participle meaning prediction. Outcome: did not generalise. Reason: rules failed to capture idiosyncratic semantic shifts and semi-productivity patterns

The semantics of past participles · UT Austin · PhD

Tried and failed

rule-based dependency parser with candidate scoring applied to natural language to formal specification translation. Reason: candidate completions lacking matching input categories were overly penalized by the negative scoring mechanism

Framework for Automatic Translation of Hardware Specifications Written in English to a Formal Language · Virginia Tech · Doctorate

Lost to a baseline

Rule-based baseline NLP (EasyCIE_GUI) achieved an F1 of only 0.43 and precision of 0.34 (at 0.59 recall), losing substantially to deep learning models (BiLSTM F1 0.64–0.66, precision 0.62–0.67).

Surgical Site Infection (SSI) Identification Across Multiple Facilities and Surgery Types Using Multimodal Data and Deep Learning · University of Washington · PhD

Considered and rejected

Considered and rejected: Rejected using only plain rule-based parsing in ChemDataExtractor due to brittle failure on minor grammatical variations and low inorganic recall (56%).

Magnetic and Superconducting Materials Discovery: Employing Data Science, Natural Language Processing and Machine Learning · Cambridge · PhD

Considered and rejected

Considered and rejected: Rejected pure rule-based comparative adjective/adverb parsing due to the complexity of building grammar rules for varied linguistic structures.

Compa: A Comparative Retrieval and Analytical Engine for Consumer Products · Texas State University · Master's

Rule-based deduction engines and heuristic abstractions lack adaptability and learning capacity

6 theses · 5 institutions

Heuristic deduction engines and rule models cannot learn from new observations, demanding extensive manual reprogramming when requirements change. As a result, synthetic rule sets fail to generalize to real operational errors and heuristic abstractions produce oversimplified models or non-minimal state spaces.

Considered and rejected

Considered and rejected: Rejected automatically distinguishing between genuinely unknown biochemical gaps and reconstruction errors in dead-end tests due to poor accuracy of previous automated heuristics.

The fundamentals of genome-scale metabolic models and their application to the study of evolution and cancer · Boston University · PhD

Considered and rejected

Considered and rejected: Rejected synthetic rule-based error injection models because their error distributions failed to generalize to real generation errors

Fine-grained evaluation for text summarization · UT Austin · PhD

Tried and failed

counterexample-guided abstraction refinement applied to partial-information game synthesis. Outcome: worse than baseline. Reason: automated refinement heuristics produce non-minimal abstract state spaces compared to manual domain-specific abstractions

Assured decison-making for autonomous systems · UT Austin · PhD

Considered and rejected

Considered and rejected: Default high dependency thresholds in the Flexible Heuristics Miner algorithm were rejected because they led to oversimplified process models in low-structured domains.

Rezeptions- und Interpretationsprozesse von Lehrpersonen bei datengestützten Entscheidungen. Exploration und Förderung · Tübingen · PhD

Considered and rejected

Considered and rejected: Rejected rule-based deduction engines (e.g. from IoIF) because semantic rules cannot learn from new observations or scale across new problem domains.

MM-ADM: A model-based approach to multidisciplinary design to support automated decision-making · Georgia Tech · PhD

Considered and rejected

Considered and rejected: Rejected simple confidence-based early-stopping heuristics and generic upweighting methods for error mitigation because they fail to capture consistent, human-understandable failure modes.

A Data-Based Perspective on Model Reliability · MIT · PhD

Rigid mathematical thresholds and deterministic rules fail in dynamic or continuous environments

5 theses · 5 institutions

Hardcoded thresholds and deterministic switching rules cannot accommodate dynamic workloads, continuous variables, or boundary conditions fairly. When deployed in non-stationary or long-horizon tasks, these inflexible policies become erratic, generate false positives, and fail outside narrow operating ranges.

Considered and rejected

Considered and rejected: Rejected rule-based heuristics and MPC for long-term operational optimization due to lack of adaptability in dynamic environments and poor scaling over long-horizon stochastic tasks.

Edge Computing in Space: Design Optimization and Reinforcement Learning Scheduling of Onboard Computing Satellites · MIT · PhD

Tried and failed

static heuristic-based threshold switching rules applied to dynamic architectural protocol selection. Outcome: worse than baseline. Reason: simple thresholds fail to capture complex workload dynamics, yielding incorrect decisions in half the cases

AI-DRIVEN ADAPTIVE DISTRIBUTED SYSTEMS IN UNTRUSTED ENVIRONMENTS · Penn · PhD

Considered and rejected

Considered and rejected: Crisp rule-based expert systems using rigid mathematical thresholds were rejected because they fail to handle boundary cases fairly and create overly complex, unmaintainable rule bases.

Strategie działania inteligentnych systemów wspierających kształcenie operujące na danych nieprecyzyjnych Strategies of operation for intelligent tutoring systems operating on imprecise data · Adam Mickiewicz University · PhD

Considered and rejected

Considered and rejected: Fixing static μ thresholds rule-based was rejected in favor of dynamically low-pass filtering synaptic weight efficacy

Building new memories using the past: Interplay between semantic and episodic memory in brains and machines · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected classical rule-based conditional programming (hardcoded angle thresholds) because it produced false positives while moving/pretending to shoot and could not generalize across diverse shooting styles.

Live Perception and Real Time Motion Prediction with Deep Neural Networks and Machine Learning · Harvard · Master's

Deterministic heuristics fail to capture uncertainty and stochasticity in human behavior

6 theses · 4 institutions

Rule-based models fall short when estimating human activity or responses because deterministic logic ignores baseline behavioral stochasticity and sensor noise. Furthermore, crowdsourced or manual rule sets encode shallow heuristics that fail on complex edge cases and slow down users without boosting decision accuracy.

Tried and failed

rule-based behavior inference applied to human response behavior under disruption. Reason: produced systematic overestimation by ignoring baseline stochasticity in human behavior

Toward a Resilient Public Transportation System: Effective Monitoring and Control under Service Disruptions · MIT · PhD

Tried and failed

heuristic training for counterfactual forecasting applied to decision making under unrepresentative baselines. Outcome: did not generalise. Reason: training failed when faced with unrepresentative baseline distributions or prospective conditional framing

FAST AND FRUGAL STATISTICAL HEURISTICS: TRANSFER OF COUNTERFACTUAL FORECASTING TRAINING WITHIN AND ACROSS DOMAINS · Penn · PhD

Tried and failed

deterministic rule-based logical models applied to human activity estimation. Outcome: worse than baseline. Reason: strict logical rules cannot handle noise and uncertainty compared to probabilistic modeling

Cognitive Human Activity and Plan Recognition for Human-Robot Collaboration · MIT · PhD

Tried and failed

extracting decision rules from human-voted behavior applied to sequential decision-making in disrupted environments. Outcome: did not generalise. Reason: crowdsourced rules encoded shallow, suboptimal heuristics with plateauing performance gains

Managing The Gig Economy Via Behavioral And Operational Lenses · Penn · PhD

Tried and failed

rule-based heuristic decision support system applied to human decision-making under degraded information. Outcome: worse than baseline. Reason: increased user response times without improving accuracy, especially for lower-performing users

Understanding and Supporting Decision Making in Denied and Degraded Environments · Georgia Tech · PhD

Tried and failed

rule-based anti-pattern heuristics for manual diagnosis applied to identifying algorithmic complexity vulnerabilities. Reason: developers could not accurately diagnose complex edge cases using manual pattern rules

Theory and Patterns for Avoiding Regex Denial of Service · Virginia Tech · Master's

Rule-based classifiers and heuristic feature selectors underperform probabilistic and learned baselines

4 theses · 4 institutions

Predefined rules and heuristic filtering struggle to model continuous attributes and complex topological relationships, leading to high false positive rates and unnecessary constraints. Across benchmark tasks like gait identification and investment classification, rule-based algorithms consistently lost to probabilistic methods and decision trees.

Tried and failed

heuristic rule-based constraint extraction applied to circuit symmetry constraint detection. Outcome: worse than baseline. Reason: produced higher false positive rates and generated unnecessary constraints compared to learned representations

Layout automation for custom integrated circuits · UT Austin · PhD

Lost to a baseline

Heuristic rules-based algorithm achieved lower overall gait event identification accuracy across locomotion modes (94.87%) compared to the unsupervised BP-AR-HMM (99.6%).

Machine Learning and Wearable Sensors for the Estimation of Biomechanical Variables Outside the Laboratory · University of Oregon · PhD

Lost to a baseline

Rule-based PART classifier (0.5005 accuracy on investment cost) lost to C4.5 Trees J48 (0.571 average accuracy) and Naive Bayes (0.5091 accuracy on investment cost)

Renewable Energy Communities: A Preference Learning Approach to Evaluate Differential Participation in Cities · Politecnico di Torino · PhD

Tried and failed

heuristic filter-based feature selection applied to transient stability classification. Outcome: worse than baseline. Reason: standard filters failed to capture complex causal topological interactions compared to Markov blanket selection

Topological changes in data-driven dynamic security assessment for power system control · Imperial · PhD

Left open by the authors

Problems the authors named and did not get to.

Left open

Extend the tree-based rule extraction heuristic to estimate continuous variables and generalize across different problem sizes. Blocker: Lack of specific target continuous variables, validation metrics, or concrete generalization methodology

A Machine Learning-Based Heuristic to Explain Game-Theoretic Models · Virginia Tech · Master's

Left open

Test whether fast-and-frugal counterfactual forecasting heuristics transfer to real-world scenarios lacking accessible ground truth. Blocker: No specific real-world domain, evaluation methodology, or benchmark dataset is defined for scenarios lacking ground truth

FAST AND FRUGAL STATISTICAL HEURISTICS: TRANSFER OF COUNTERFACTUAL FORECASTING TRAINING WITHIN AND ACROSS DOMAINS · Penn · PhD

Left open

Adapt the rule-extraction and hierarchical decision tree heuristic to explain policy functions in reinforcement learning models. Blocker: The proposal is an exploratory direction without a specified target RL environment, policy model, or evaluation benchmark.

A Machine Learning-Based Heuristic to Explain Game-Theoretic Models · Virginia Tech · Master's

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