Report:QPAT/Search Syntax/Allowed Operators/Truncation or Wildcard Operators

Truncation operators are essential to keyword searching. References can be easily missed if they do not contain the exact terms covered by a keyword string, which means that users must take variations in spelling, plurals, and even common typos into account, and truncation operators provide an easy way to do that.

QPAT’s truncation features are especially good. Most search systems permit unlimited truncation at the end of a word (right truncation), but not all permit unlimited truncation at the beginning or middle of a term as QPAT does (left- or internal truncation). These are important features, especially for life science and chemical searches, where medical and chemical terms can support a variety of prefixes.

QPAT’s unlimited truncation feature can be applied internally provided that the beginning and ending stems are each at least three letters long. As a simple example, take the search term “pre+tion.” As a text search term in the FamPat database, the system returned over 943,000 results, having pulled up keyword hits like “prediction,” “prevention,” “prehydration,” and “preparation.” Obviously, this example is prohibitively inclusive, but the utility of this feature might extend to searches in chemistry, life sciences, or biotechnology, where (English-language) compound terms for compounds, enzymes, etc. are often created out of word stems with generally accepted meanings.

Notably, the QPAT does not include a stemming operator, which automatically searches for grammatical extensions to a given word stem based on an algorithm constructed partially from a database of English-language prefixes and suffixes. The exclusion of a stemming operator should not be seen as a major disadvantage; in most cases the more inclusive truncation operator, which finds any word incorporating a given portion (regardless of whether the variations are possible in English grammar), will do the same job. Normal truncation offers less uncertainty about what terms might have been excluded; because stemming works from defined grammar rules, it might exclude unusual terms that could be relevant.