Using Boolean search

Boolean searching allows you to combine up to three search terms.

For example: submitting a query for voyage will result in a search for all works in the database in which that term occurs. If the term gold was added using the AND operator to the previous example search, the search would be limited to works in which both voyage and gold appear somewhere in the text.

Precedence of Boolean operators

Boolean expressions are operated on from left to right. This means that you will need to take some care in formulating your search.

For example: You wish to find any texts that mention the word tobacco AND either the word Indian OR trade. Your search should be formulated as: Indian OR trade AND tobacco.

Understanding the results

Since the search works from left to right, the search will first look for the set of texts that contains EITHER trade or tobacco.

Then the search will look within that set of texts for the ones that also mention tobacco. Those texts will be your results set.

If you had formulated your search as tobacco AND Indian OR trade you would have gotten a very different set of results. Why?

Since the search works from left to right, the search would have first looked for the set of texts that contains BOTH the words tobacco and Indian. Next it would have looked for the texts that contain the word trade. Then it would combine those two sets of results and eliminated the duplicates to give you your results. This means you would have a whole set of texts that contain trade but make no mention of tobacco. You can also use the Boolean NOT option look for occurrences where a term is used without the presence of another term.

For example, a search for witch AND England NOT colony will retrieve texts in which witches in England, not the colonies, are mentioned.

Related topics:

Simple search
Proximity search
Searching regions