Add title validation with dcterms:title support

docs/concepts/how-it-works.md

@@ -46,6 +46,33 @@ Parts: ["MUC1 oncoprotein", "nuclear targeting"]
 # Both parts must exist in the reference
 ```
 
+### 4. Title Validation
+
+In addition to excerpt/quote validation, the validator can verify reference titles using **exact matching** (not substring). Titles are validated when:
+
+- A slot implements `dcterms:title` or has `slot_uri: dcterms:title`
+- A slot is named `title` (fallback)
+
+**Example:**
+```yaml
+reference_title: "MUC1 oncoprotein blocks nuclear targeting of c-Abl"
+```
+
+Title matching uses the same normalization as excerpts (case, whitespace, punctuation, Greek letters) but requires the **entire title to match**, not just a substring.
+
+```python
+# These match after normalization:
+expected = "Role of JAK1 in Cell-Signaling"
+actual = "Role of JAK1 in Cell Signaling"
+# Both normalize to: "role of jak1 in cell signaling"
+
+# These do NOT match (partial title):
+expected = "Role of JAK1"  # Missing "in Cell Signaling"
+actual = "Role of JAK1 in Cell Signaling"
+```
+
+See [Validating Reference Titles](../how-to/validate-titles.md) for detailed usage.
+
 ## Why Deterministic Matching?
 
 ### Not Fuzzy Matching
@@ -171,10 +198,17 @@ classes:
         slot_uri: linkml:excerpt  # Marks as quoted text
       reference:
         slot_uri: linkml:authoritative_reference  # Marks as reference ID
+      reference_title:
+        slot_uri: dcterms:title  # Marks as reference title (optional)
 ```
 
 When LinkML validates data, it calls our plugin for fields marked with these URIs.
 
+The plugin discovers fields via:
+- `implements` attribute (e.g., `implements: [dcterms:title]`)
+- `slot_uri` attribute (e.g., `slot_uri: dcterms:title`)
+- Fallback slot names (`reference`, `supporting_text`, `title`)
+
 ## Editorial Conventions
 
 ### Square Brackets `[...]`

docs/how-to/validate-titles.md

@@ -0,0 +1,146 @@
+# Validating Reference Titles
+
+This guide explains how to validate that reference titles in your data match the actual titles from the source publications.
+
+## Overview
+
+Title validation ensures that when you cite a reference with a title, that title matches what the publication actually has. Unlike excerpt validation (which uses substring matching), title validation uses **exact matching after normalization**.
+
+## When to Use Title Validation
+
+Title validation is useful when:
+
+- Your data includes reference titles that should match the source
+- You want to catch typos or outdated titles
+- You need to verify metadata accuracy in curated datasets
+
+## Schema Setup
+
+Mark title fields in your LinkML schema using `dcterms:title`:
+
+### Using `implements`
+
+```yaml
+id: https://example.org/my-schema
+name: my-schema
+
+prefixes:
+  linkml: https://w3id.org/linkml/
+  dcterms: http://purl.org/dc/terms/
+
+classes:
+  Evidence:
+    attributes:
+      reference:
+        implements:
+          - linkml:authoritative_reference
+      reference_title:
+        implements:
+          - dcterms:title
+      supporting_text:
+        implements:
+          - linkml:excerpt
+```
+
+### Using `slot_uri`
+
+```yaml
+classes:
+  Evidence:
+    attributes:
+      reference:
+        slot_uri: linkml:authoritative_reference
+      title:
+        slot_uri: dcterms:title
+      supporting_text:
+        slot_uri: linkml:excerpt
+```
+
+## Example Data
+
+**data.yaml:**
+```yaml
+- reference: PMID:16888623
+  reference_title: "MUC1 oncoprotein blocks nuclear targeting of c-Abl"
+  supporting_text: "MUC1 oncoprotein blocks nuclear targeting"
+```
+
+**Validate:**
+```bash
+linkml-reference-validator validate data \
+  data.yaml \
+  --schema schema.yaml \
+  --target-class Evidence
+```
+
+## What Gets Normalized
+
+Title matching allows for minor orthographic variations:
+
+| Variation | Example |
+|-----------|---------|
+| **Case** | `"JAK1 Protein"` matches `"jak1 protein"` |
+| **Whitespace** | `"Cell  Signaling"` matches `"Cell Signaling"` |
+| **Punctuation** | `"T-Cell Receptor"` matches `"T Cell Receptor"` |
+| **Greek letters** | `"α-catenin"` matches `"alpha-catenin"` |
+| **Trailing periods** | `"Study Title."` matches `"Study Title"` |
+
+## Title-Only Validation
+
+You can validate titles without excerpts. If your data has reference and title fields but no excerpt field, the validator will validate the title alone:
+
+```yaml
+classes:
+  Reference:
+    attributes:
+      id:
+        implements:
+          - linkml:authoritative_reference
+      title:
+        implements:
+          - dcterms:title
+```
+
+```yaml
+- id: PMID:16888623
+  title: "MUC1 oncoprotein blocks nuclear targeting of c-Abl"
+```
+
+## Combined Validation
+
+When both title and excerpt fields are present, both are validated together:
+
+1. The excerpt is checked for substring match in the reference content
+2. The title is checked for exact match (after normalization) against the reference title
+
+If either fails, validation fails with a specific error message.
+
+## Error Messages
+
+### Title Mismatch
+
+```
+Title mismatch for PMID:16888623: expected 'Wrong Title' but got 'MUC1 oncoprotein blocks nuclear targeting of c-Abl'
+```
+
+### Reference Has No Title
+
+```
+Reference PMID:99999999 has no title to validate against
+```
+
+## Differences from Excerpt Validation
+
+| Aspect | Title Validation | Excerpt Validation |
+|--------|------------------|-------------------|
+| **Matching** | Exact (after normalization) | Substring |
+| **Partial matches** | Not allowed | Allowed with `...` |
+| **Editorial notes** | Not supported | `[brackets]` removed |
+| **Use case** | Metadata accuracy | Quote verification |
+
+## Best Practices
+
+1. **Use exact titles**: Copy the title exactly from the source
+2. **Don't abbreviate**: Title must match completely
+3. **Check special characters**: Greek letters, subscripts, etc.
+4. **Verify after fetching**: The cached reference shows the actual title

docs/index.md

@@ -9,6 +9,7 @@ linkml-reference-validator ensures that text excerpts in your data accurately ma
 - **Deterministic validation** - No fuzzy matching or AI hallucinations
 - **Multiple reference sources** - PubMed, DOIs, local files, and URLs
 - **Editorial convention support** - Handles `[clarifications]` and `...` ellipsis
+- **Title validation** - Verify reference titles with `dcterms:title`
 - **Multiple interfaces** - CLI for quick checks, Python API for integration
 - **LinkML integration** - Validates data files with `linkml:excerpt` annotations
 - **Smart caching** - Stores references locally to avoid repeated API calls

docs/quickstart.md

@@ -111,6 +111,7 @@ linkml-reference-validator validate text \
 - **Automatic Caching**: References cached locally after first fetch
 - **Editorial Notes**: Use `[...]` for clarifications: `"MUC1 [mucin 1] oncoprotein"`
 - **Ellipsis**: Use `...` for omitted text: `"MUC1 ... nuclear targeting"`
+- **Title Validation**: Verify reference titles with `dcterms:title`
 - **Deterministic Matching**: Substring-based (not AI/fuzzy matching)
 - **PubMed & PMC**: Fetches from NCBI automatically
 - **DOI Support**: Fetches metadata from Crossref API
@@ -121,5 +122,6 @@ linkml-reference-validator validate text \
 
 - **[Tutorial 1: Getting Started](notebooks/01_getting_started.ipynb)** - CLI basics with real examples
 - **[Tutorial 2: Advanced Usage](notebooks/02_advanced_usage.ipynb)** - Data validation with LinkML schemas
+- **[Validating Reference Titles](how-to/validate-titles.md)** - Verify titles with `dcterms:title`
 - **[Concepts](concepts/how-it-works.md)** - Understanding the validation process
 - **[CLI Reference](reference/cli.md)** - Complete command documentation

mkdocs.yml

@@ -35,6 +35,7 @@ nav:
       - Validating Entrez Accessions: how-to/validate-entrez.md
       - Validating DOIs: how-to/validate-dois.md
       - Validating URLs: how-to/validate-urls.md
+      - Validating Reference Titles: how-to/validate-titles.md
       - Using Local Files and URLs: how-to/use-local-files-and-urls.md
       - Adding a New Reference Source: how-to/add-reference-source.md
   - Concepts: