Domain-Adapted Extraction Pipeline

Updated 25 December 2025

The paper presents a modular IE system that integrates fine-tuning, custom bi-LSTM-CRF, and deep SRL for high-precision extraction in specialized domains.
It details a multi-stage workflow combining parallel entity extraction, verb-pattern relation extraction, and dynamic knowledge graph anchoring for actionable insights.
The system demonstrates robust performance with F1 scores around 72% and adaptability across regulatory, scientific, and business contexts.

A domain-adapted extraction pipeline is a modular information extraction (IE) system that integrates domain-specific adaptation into the architecture, training, and deployment of automated extraction components. Its purpose is to enable high-precision extraction of entities, relations, and events from text in highly specialized, dynamic, or otherwise non-standard domains, in contrast to exclusively relying on generic, off-the-shelf NLP models or knowledge-driven ontologies. Domain adaptation is achieved through fine-tuning, constrained schema integration, hybrid lexical–semantic features, or explicit injections of domain knowledge, ensuring that the extractor is robust both to in-domain specifics and evolving requirements. Such pipelines are particularly valuable in regulatory, scientific, medical, and business contexts, where input styles and semantic targets deviate significantly from general-domain corpora (Khetan et al., 2021).

1. High-Level System Architecture

The paradigm exemplified in "Knowledge Graph Anchored Information-Extraction for Domain-Specific Insights" (Khetan et al., 2021) is a multi-stage, hybrid pipeline:

Input: Unstructured, domain-rich text (e.g., regulatory filings, Federal Register articles).
Entity and Actor Extraction (Parallel):
- Custom bi-LSTM-CRF for named entity recognition (NER).
- Attention-based deep Semantic Role Labeling (SRL) for actor/action detection.
Entity Filtering: Retain only entities detected by both NER and SRL modules (precision maximization).
Automated Verb-Based Relationship Extraction: For each entity pair, apply a verb-pattern extractor, leveraging dependency parsing and template matching to enumerate candidate binary relations.
Data Model Instantiation: Assembles extracted triples into a task-specific schema, encoding types such as event, actor, value, and date.
Knowledge Graph Anchoring and Update: Maps string mentions to existing knowledge graph (KG) nodes, adds nodes/edges, increments edge weights, and incorporates external domain metadata (e.g., NIC bank registry).
Notification and Insight Generation: User-defined or lexicon-based rules subscribe to KG changes, triggering notifications and enabling higher-order analytic summarization.

This data flow forms a comprehensive extraction-to-insight pathway adapted explicitly for fast-changing, high-stakes environments where traditional ontology construction is too slow or brittle.

2. Model Components and Mathematical Formulations

2.1 bi-LSTM-CRF Sequence Labeling

The core entity extractor is a standard bi-LSTM-CRF hybrid. For an input sequence $x = (x_1,\ldots,x_T)$ :

Forward and backward LSTMs produce hidden vectors $h_{f,t}$ , $h_{b,t}$ , concatenated as $h_t = [h_{f,t}; h_{b,t}]$ .
Emission score for tag $k$ at $t$ : $e_t(k) = W_\mathrm{em} h_t + b_\mathrm{em}$ .
Transition matrix $A \in \mathbb{R}^{K\times K}$ encodes tag-to-tag transitions.
Score for tag sequence $y = (y_1,\dots,y_T)$ : $s(x,y) = \sum_{t=1}^T [A_{y_{t-1},y_t} + e_t(y_t)]$ , with $y_0 = \mathrm{START}$ .
CRF log-likelihood loss: $L_{\mathrm{CRF}}(\theta) = - \log \frac{\exp s(x,y^*)}{\sum_{y'} \exp s(x,y')}$ , where $y^*$ is gold.
Inference is by Viterbi: $\hat y = \arg\max_y s(x,y)$ .

2.2 Attention-Based Deep SRL

For a given predicate at token $i$ :

Compute BiLSTM hidden state sequence $H = [h_1, \dots, h_T]$ .
Additive attention: $\alpha_t = \mathrm{softmax}(u^\top \tanh(W_1 h_t + W_2 h_i + b))$ .
Context vector $c_t = \sum_{j=1}^T \alpha_{t,j} h_j$ .
Classification: $P(\mathrm{role}_t \mid x,p) = \mathrm{softmax}(V[c_t; h_t] + b')$ .

2.3 Verb-Pattern Relationship Extractor

Given entity pair $(e_1,e_2)$ in sentence:

Dependency parse identifies the shortest path.
Apply pattern templates (e.g., $(e_1) \leftarrow \mathrm{nsubj} \leftarrow \mathrm{verb} \rightarrow \mathrm{dobj} \rightarrow (e_2)$ ).
Each matched pattern yields candidate $R = (e_1, \mathrm{verb}, e_2)$ , scored by features (path length, POS, object case).
Accept $R$ if score $\geq \theta$ .

3. Knowledge Graph Integration and Update

Domain-adapted extraction does not end with relation triples; these must be linked to a persistent, evolving knowledge graph (KG):

Node Schema: Entities (e.g., RegulatoryAuthority, Bank, ThresholdEvent).
Edge Types: Relations such as impacts, issues, changes.
Anchoring: Mentions are resolved to nodes via exact string match or type match. If no match, a new node is inserted.
Edge Updates: For each triple $(s, r, o)$ , if the edge $(s', r, o')$ exists, increment its weight; else insert with weight $w_0$ .
Attribute Augmentation: Metadata from auxiliary sources (NIC registry: assets, address, regulator) is attached to relevant nodes.
Deduplication: Nodes with string similarity above a threshold $\tau$ are merged in periodic sweeps.

Anchoring KGs to extracted facts allows for cross-document aggregation and user-triggered rule notifications.

4. Domain Adaptation Strategies and Training

Key adaptation techniques used in the pipeline:

Entity Extraction: The bi-LSTM-CRF is fine-tuned on a hybrid corpus—standard NER data (CoNLL 2017) plus 131 manually annotated in-domain articles. Training uses dropout $=0.5$ , learning rate $=10^{-3}$ (Adam), batch size $32$, for $15$ epochs.
SRL/Verb-based Extractor: Applied off-the-shelf on the new domain, occasionally with additional predicate-level supervision on in-domain text. No full re-training or domain-specific tuning required beyond the task-specific data.
No New Ontology Injection: Instead of hand-building or learning new ontologies, the system relies on its knowledge graph to evolve dynamically via incoming, instance-level data and simple heuristics.
Human-in-the-loop Validation: Since recall is prioritized over precision, downstream domain experts manually prune low-confidence extractions, resulting in higher net value for users.

5. Performance, Evaluation, and Limitations

Preliminary manual validation, as reported in (Khetan et al., 2021):

Component	Recall (%)	Precision (%)	F1 (%)
Entity Extraction	~85	~70	~77
Relation Extraction	~80	~65	~72
End-to-End	–	–	~72

Summarization Ratio: The output yields an 8–12 $\times$ compression of document length.
Usability: The pipeline is designed for high recall, allowing for accurate downstream insights with tolerable manual correction costs.
Metrics: Standard P/R/F1 metrics are being systematically collected; pipeline is optimized for timely insight over ultra-high precision.

Limitations:

Ontology evolution is driven by heuristics and string matching, without strong semantic resolution or advanced contexual disambiguation.
Relation extraction leverages shallow dependency patterns rather than full neural relation extraction, possibly limiting recall for complex constructs.
No explicit learning of event schemas beyond the data model in use.

6. Broader Context and Comparative Implementations

While the "Knowledge Graph Anchored Information-Extraction" architecture is tailored to regulatory business text, the modular, domain-adaptive extraction paradigm generalizes to other fields:

Biomedical RE: Pipelines fine-tune BERT-based models on small, high-quality biomedical corpora with domain-specific schema or utilize adapter modules or hybrid LLM–rule systems (Khettari et al., 10 Jun 2025).
Business Documents: Rapidly adaptable BERT-based sequence labelers achieve high F1 with less than 100 annotated documents per new schema (Zhang et al., 2020).
Scientific Event Extraction: Multi-stage pipelines segment text into narrative events and apply span and argument extractors, with optional domain adaptation via transformer adapters (Dong et al., 19 Sep 2025).

The distinctive advantage of domain-adapted extraction pipelines is their operational flexibility: by tightly integrating domain knowledge—whether through training regimes, schema instantiation, or knowledge graph updates—they dramatically outperform generic "one-size-fits-all" models in both efficiency and utility for end users.

7. Representative Pseudocode and Workflow

The following pseudocode, adapted from (Khetan et al., 2021), encapsulates the core extraction loop:

for article in incoming_stream:
    ner_entities = biLSTM_CRF(article)
    srl_actors   = deepSRL(article)
    candidates   = intersect(ner_entities, srl_actors)
    triples      = []
    for (e1,e2) in all_pairs(candidates):
        rels = verbBasedExtractor(article, e1, e2)
        for r in rels:
            triples.append( (e1, r, e2) )
    instance = fillDataModel(triples)
    KG = anchorToGraph(instance, existingKG)
    notifications = generateAlerts(KG, userRules)
    emit(notifications)

This represents a robust sequence for practical deployment in highly dynamic domains, providing a validated method for scalable, high-throughput, and knowledge-grounded information extraction (Khetan et al., 2021).