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This page describes the recommended syntax for searching in NPS Archive: Calhoun.




The Basic Search and Advanced Search features of Calhoun are powered by Apache's Lucene text search engine.  View full documentation on Apache Lucene - Query Parser Syntax or check out some of the quick tricks and tips below.

Multiple search terms are interpreted as if there was AND between each word, not OR.

"Refine By" filters represent DSpace 5.1 "Discovery" features, which are powered by Solr.  View full documentation on the Solr Wiki.

As of this date (December 2017), Calhoun is based on DSpace 6.

Basic Search

The basic search box is provided at the center on the Calhoun Home page.   Entering terms into this search box will perform a full-text search unless syntax is used to perform a more specific query (see below). Hit return or the magnifying glass icon to execute the search. Note that the magifying glass icon will take you to a page where additional search features are available.


Building your search using filters

Access Advanced Search features by clicking on the magnifying glass icon. This interface performs complex queries using Filters ("Refine By").  A drop-down menu allows for setting the search in  "All of Calhoun" or just one part.  Use other drop-down menus to set your search terms in specific fields. Use the plus or minus to add or subtract the number of filters.  Click Go when using only the top search box.  Click Apply to apply filters.

Advanced Searches may also be carried out with the use of query syntax (see below).

Query Syntax

Complex queries can be carried out with the syntax provided by Lucene's text search engine.  These queries can be set in the first (top) search box, like this: 

Click Go to execute the search.

Phrase searching

Double quotes must surround phrases or words within the phrase will be treated as separate search terms in full text.  This means the query below would return results from full text, unless a the search was set in a specific field, such as the title or abstract.

Example: if you wanted to search for the phrase decision tree then it should appear as follows.

"decision tree"

Search within a specific field

You can search within a specific field. For example, if you wanted to search for the phrase decision tree in the title field you would input:

title:"decision tree"

Search for a specific author:

If you wanted to search for a name in the author field you would input:


Search for a specific advisor. (Use this search to identify a results set of theses advised by a specific advisor):

If you wanted to search for a name in the advisor field you would input:


Using a wildcard

A single character wild card is denoted by ?, while a multiple character wildcard is denoted by * . (Don't use this feature with double quotes, or it will treat your wildcard search as an exact phrase, that is, as a word containing ?  or *. Not

A single character wildcard search to retrieve woman, women in full text:


A multiple character wildcard search, to retrieve secure, security in the title field:


Fuzzy search

A fuzzy search works only with single terms and is appropriate when you want to cast a broad net and is denoted by ~

This may be a useful if you are searching for an acroynm but are unsure about its exact spelling and usage:

A fuzzy search:


You can specifiy how fuzzy the search should be by adding a value from 0 (more fuzzy) to 1 (less fuzzy).  The default is 0.5


Proximity search

A proximity search allows terms to be searched for on the condition that each word specified is within a certain number of words away from the other(s). A proximity search is denoted with a ~ at the end of a set of words in double quotes, and a value that indicates the maximum numbers of words that separate the terms.

For example, if you wanted to search for "decision" and "tree" within the same sentence you could input:

"tree decision"~10

Boosting a search term

If you are performing a multiple term search, you can increase the weight of a term's relevance to the search by using the ^ symbol and a boost factor.

For example,

"decision tree" "nps"^5

Boolean operators

Boolean operators can add logical structures to searches. Available operators include AND, +, OR, NOT, and -

Operators must be in upper case: AND, NOT, OR

For example,

decision AND tree

...will return documents that contain both terms in full text.

decision +tree

...will return documents that contain tree and also any that include decision, in full text

decision OR tree

...will return documents that contain decision or tree, in full text

decision NOT tree

...will return documents that contain decision but not tree.

decision -tree

...will also return documents that contain decision but not tree.

title:decision AND title:tree

...will return documents that contain decision and tree, with both terms in the title field.


Logical structures can be grouped togethor by using parentheses.

For example,

"decision tree" AND ("Naval Postgraduate School" OR NPS) 

Date ranges

Find a span of documents published during a period of time.  DateIssued is the publish date.

For example,

dateIssued:[1986 TO 1990] 

Arrange your results

You can arrange your results by Relevance, Title Ascending/Descending, Issue Date Ascending/Descending, Added Date Ascending/Descending, Handle Ascending/Descending, and specify how many results appear on a page. Look for the "gear" icon to do this.

Note: Issue Date is the document publication date.  Added Date is the date on which the document was added to Calhoun.  Handle is by the numerical order of each "Handle" or assigned Calhoun link.  Calhoun links look like this: . 10945/45903 is the Handle.


Sets of results in Calhoun produce usable links.  Make a search, refine it, set the number of items to display on a single page, then look for the link in your browser window.  This link may be quoted and used in other pages and will always display results of your search, even if new, relevant results are added in future.

The link may be quite long:

Try it!  Click that long link, and once you are in Calhoun, change the author name in the search box to any author name.  Click GO, view the results, then look for the link to that set in your browser.  This link may be used in web pages to display an up-to-date list of publications by that author.  Calhoun links can be shortened using services such as