Search Basics

Search Basics

See Also:

Search Tips, Search FAQs, Search Problem-Solver, Search Command Reference

This section explains simple search queries, precedence, stemming, using wildcards, and weighting your search terms.

Complex Search Syntax

Search queries that use operators other than AND, OR, NOT, +, -, " (double-quotation marks), and parentheses () are part of the complex search syntax. You must precede complex search queries with VQL: and double-quote the search query. For example:

VQL:"[50] aniline, [10] textile, [80] \"dye technology\""

Note the double-quotes around the entire query and the backslashes that precede and escape the double-quotes used within the query.

Simple Search Queries

Summary: Not case-sensitive. Separate words and phrases with commas.

Capital letters (case): yet2.com pays no attention to uppercase (capital) or lowercase (small) letters. Your searches are not case-sensitive. The following are all the same:

Polymer
polymer
PoLyMeR

Entering phrases: Always double-quote a phrase. Otherwise, yet2.com will search for the separate words.

"drilling rig"

Separating phrases and words: Generally, separate words and phrases with a space. A space acts as the AND operator. You will find all listings that contain all the words you type. The following query line consists of a word, another word, and a two-word phrase:

aniline textile "dye technology"

yet2.com interprets this query as "aniline" AND "textile" AND "dye technology." yet2.com interprets the comma as the operator OR. (See "OR".) Your search results will contain those documents that include any of the three terms.

Important: Multiple terms separated by commas (OR) make your search broader. To narrow your search to documents that must include all the search terms, use the operator AND: aniline AND textile AND dye technology. An even more accurate way of narrowing your search is to use the complex syntax <ACCRUE> operator or the <ALL> operator: VQL:"<ACCRUE>(aniline, textile, \"dye technology\")"; VQL:"aniline <ACCRUE> textile <ACCRUE> \"dye technology\""; or VQL:"<ALL>(aniline, textile, \"dye technology\")". You must use angle brackets with <ACCRUE> and <ALL>. Note the backslashes that you must use before a double-quote that appears inside a complex syntax query.

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This document OR that document: You may want to retrieve documents that contain various words and phrases. Use the OR operator:

aniline OR textile OR dye technology

Your search results will contain documents that contain at least one of the search terms. See "OR".

Exclude some documents: Use the NOT operator to make sure that a search term does not appear in the documents returned in your search results:

aniline AND NOT textile

Important: All operators other than AND (+), OR (,), and NOT, are part of the complex syntax and must appear between angle brackets:

<STEM>
<NEAR/5>
<MANY>

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Precedence

Summary: AND takes precedence over OR. Use parentheses to control the order of evaluation.

yet2.com evaluates your search expression from left to right, but evaluates terms joined by the AND operator before it evaluates terms joined by the OR operator. You can control precedence further by using parentheses ( ).

Table 1. AND, OR, and precedence

Expression

Finds...

a AND b

Documents that contain both a and b

a OR b

Documents that at least contain a or that at least contain b (the documents can contain both)

a AND b OR c

Documents that contain both a and b; or documents that contain c

a OR b AND c

Documents that contain both b and c; or documents that contain a

(a OR b) AND c

Documents that contain either a or b, and of those documents, documents that also contain c

(a AND (b OR c)) OR d

Documents that contain either b or c, and of those documents, documents that also contain a; or those documents that contain d

Note: Evaluation of nested parentheses begins with the innermost pair.

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Stemming

Summary: yet2.com looks up various word endings automatically. Stop that behavior with " ".

When you enter a word or phrase, of course yet2.com looks for that word or phrase. For example, if you enter oil, yet2.com looks for documents that contain the word "oil."

Automatically, yet2.com also looks for variations on the endings for "oil," such as oils, oiling, and oiler. This process is called stemming. yet2.com stems both words that stand alone and word that appear in phrases, so if you enter

"drilling rig"

yet2.com automatically looks for variations on the word drilling and for variations on the word rig. (Click here for more information.)

Important: Stemming works only on the tail of a word, so your search finds oils, oiling, and oiler, but does not find toil, boil, and so forth. Stemming also works only on complete words, so entering "boi" does not automatically find boiler, boiling, and so forth. For that function, see "Wildcards".

To control stemming:

Turn off stemming by putting each search term in double quotation-marks:

"drilling rig", "diamond-bit technology"

Force stemming by putting each search term in single quotation-marks or by using the <STEM> operator:

VQL:"<STEM>drilling <STEM>rig, <STEM>diamond-bit technology"
´drilling´ ´rig´, ´diamond-bit´ technology

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Wildcards

Summary: Search on partial words or characters.

Wildcards are different from stemming in that stemming finds variations on a root word; wildcards can find explicit variations on partial words or groups of characters. The two most common wildcard characters are:

? (question mark), which stands in for any single alphanumeric character (the printable ASCII character set).
* (asterisk), which stands in for any string of alphanumeric characters.

For example:

???rose

finds sucrose and levrose (each having three characters before "rose"), but does not find dextrose, which has four characters before "rose." And:

rig*

finds rig, rigs, and rigger.

There are additional wildcard characters that require the <WILDCARD> command and the complex search syntax. For more information on wildcard characters, see Table 2.

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Weighting Your Search Terms

Summary: Control the importance of each search term by putting a number 1-100 in front of the word in square brackets: [45] drilling

You can weight each search term in your search expression by prefixing it with a number between 1 and 100 in square brackets. The higher the number, the more important the expression during evaluation. Weighting is part of complex search syntax. You must precede such queries with VQL:

VQL:"[50] aniline, [10] textile, [80] \"dye technology\""

The weighting numbers do not need to add up to 100.
Numbers do not affect stemming or wildcards:

VQL:"[50] \"aniline\", [10] textile, [80] dy* technology"

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Table 1. AND, OR, and precedence
Expression	Finds...
a AND b	Documents that contain both a and b
a OR b	Documents that at least contain a or that at least contain b (the documents can contain both)
a AND b OR c	Documents that contain both a and b; or documents that contain c
a OR b AND c	Documents that contain both b and c; or documents that contain a
(a OR b) AND c	Documents that contain either a or b, and of those documents, documents that also contain c
(a AND (b OR c)) OR d	Documents that contain either b or c, and of those documents, documents that also contain a; or those documents that contain d Note: Evaluation of nested parentheses begins with the innermost pair.


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