03 · What You Need to Know
How Generative AI Can Help Construct Boolean Literature Searches
What Is a Boolean Search String?
A Boolean search string is a structured expression that combines search terms using logical operators. These operators tell a search system how terms or groups of terms should relate to one another.
Boolean searching is widely used in scholarly databases because it allows researchers to make retrieval decisions explicit. Instead of submitting a broad question, researchers specify which concepts must appear together and which alternative expressions can satisfy a particular concept.
The three familiar Boolean operators are AND, OR, and NOT. Their exact implementation can vary by search platform, particularly when combined with field restrictions, phrase searching, proximity operators, and database-specific syntax.
| Operator |
Logical function |
Illustrative expression |
| AND |
Requires both specified conditions to be satisfied |
faculty AND "generative AI" |
| OR |
Accepts either or both of the specified alternatives |
faculty OR lecturers |
| NOT |
Excludes records satisfying a specified condition |
AI NOT robotics |
AND generally narrows retrieval when it adds a requirement, while OR generally broadens retrieval by accepting alternatives. NOT removes records meeting an exclusion condition, which can be useful but potentially hazardous.
These relationships describe Boolean logic. Actual result counts can also be affected by database mapping, query expansion, field selection, and other retrieval features.
Why Should Search Strings Begin With Concepts Rather Than Operators?
A common mistake is to ask AI for a complete Boolean expression before deciding what the search should represent.
Suppose the research question is: "What factors influence university faculty members' trust in generative AI for teaching?"
The researcher might identify three searchable concepts: university faculty, generative AI, and trust. Each concept can then be represented by a group of candidate expressions.
For the population, relevant terms might include faculty, lecturers, professors, and academic staff. For the technology, possible expressions include generative AI, generative artificial intelligence, and ChatGPT. For the trust construct, candidates include trust, distrust, and perceived trustworthiness.
These terms still require conceptual evaluation. ChatGPT represents a particular generative AI system rather than the entire technology category. Likewise, perceived reliability may be related to trust without being equivalent to it.
AI can help identify and organize candidate search terminology, but the researcher must determine which expressions belong within the intended conceptual boundaries.
How Do AND and OR Work Together?
Within a conceptual group, alternative expressions are commonly combined using OR. Different concept groups are then combined using AND when the search requires their intersection.
For example, a preliminary search might be written as:
This is an illustrative expression, not a validated database strategy. Whether it retrieves an appropriate set of studies depends on the searchable fields, indexing arrangements, and the actual language used in relevant publications.
The expression also does not mean that every retrieved study examines trust as its principal outcome. A paper may mention all three concepts without investigating the relationship of interest.
Why Are Parentheses Important?
Parentheses establish how terms are grouped and which logical conditions are evaluated together.
Compare these expressions:
faculty AND "generative AI" OR ChatGPT
faculty AND ("generative AI" OR ChatGPT)
The second expression explicitly requires the faculty concept together with either technology expression. The first may be interpreted according to the database's operator precedence rules, potentially retrieving records about ChatGPT that do not satisfy the faculty condition.
Operator precedence differs across search platforms, so researchers should not assume that an ungrouped query will behave identically everywhere.
AI can help inspect grouping logic, but the researcher should verify the final expression against the database's official search documentation.
Should You Use NOT to Remove Irrelevant Studies?
NOT can exclude records containing unwanted concepts, but it should be used cautiously, particularly in sensitive searches.
Suppose a researcher studying generative AI in education decides to exclude robotics-related publications using NOT robotics.
A relevant study comparing generative AI with educational robotics could be removed merely because its record contains the excluded term.
This illustrates an important limitation: Boolean exclusion operates on matching conditions, not on the researcher's substantive judgment about whether a study is eligible.
Watch Out
Do not use NOT merely because a term appears frequently in irrelevant search results. First determine whether excluding that term could also remove eligible studies. For comprehensive evidence syntheses, overly aggressive exclusion can reduce retrieval sensitivity.
Can AI Add Quotation Marks, Truncation, and Proximity Operators?
Yes, but these features are not universally implemented in the same way.
Quotation marks commonly indicate phrase searching, although their precise behavior depends on the database. Truncation symbols can retrieve variations of a word stem, while proximity operators may specify how closely terms must occur within a record.
For example, a database might support a truncation expression intended to retrieve educator, educators, or educational. However, the same stem could retrieve additional words that are not conceptually suitable.
Some platforms support proximity searching through operators such as NEAR or W, but the accepted notation and interpretation vary.
AI-generated expressions should therefore be treated as proposed syntax rather than automatically executable commands.
A reliable prompt should name the destination database and instruct the AI to distinguish verified syntax from features requiring confirmation.
Can AI Build Search Strings for PubMed, Scopus, and Web of Science?
AI can draft queries for these databases, but a generic Boolean expression is not necessarily portable between them.
PubMed supports field tags and Automatic Term Mapping. Scopus and Web of Science offer their own field codes, search operators, and indexing arrangements.
For example, a query restricted to titles and abstracts may require different syntax across platforms. A field restriction that works in one database might be rejected or interpreted differently in another.
Researchers should use the intended database's current documentation and test the generated query directly in that platform.
When a strategy must be used across several databases, translating the search strategy between platforms becomes a separate methodological task.
How Can You Tell Whether an AI-Generated Search String Is Good?
A syntactically valid query is not necessarily a good search strategy.
Researchers should evaluate whether the expression accurately represents the research question, retrieves known relevant studies, and avoids unnecessary restrictions.
One useful technique is to assemble a small set of known relevant publications before finalizing the search. Test whether the proposed strategy retrieves those records from databases in which they are indexed.
If a known relevant paper is missing, investigate whether the problem involves terminology, indexing, field restrictions, or the combination of concepts.
Search result counts can provide diagnostic information, but they are not a direct measure of quality. A query retrieving thousands of records may be appropriately sensitive, while a query retrieving only a few records may be either highly focused or seriously restrictive.
For systematic reviews, methodological guidance such as the Cochrane Handbook and the PRESS guideline can help researchers evaluate the structure and quality of search strategies.
Can AI Validate Its Own Boolean Search String?
AI can identify apparent logical inconsistencies, missing parentheses, duplicated terms, or potential conceptual problems. However, such checking is not equivalent to executing the query and evaluating its retrieval performance.
A language model may confidently approve a search expression containing unsupported syntax or inappropriate term combinations.
Researchers should distinguish three forms of checking:
Logical review examines whether operators and groupings represent the intended relationships.
Syntax verification establishes whether the destination database supports the proposed expression.
Retrieval testing examines what the database actually returns and whether known relevant publications can be found.
AI can assist with all three activities, but authoritative documentation and actual database results remain necessary for verification.