Using "not" in your search

DISCO’s search engine goes down the precedence list of the four search term connectors:

1. Proximity: /​
2. AND and NOT: &​ %
3. OR: [​space]

One by one, evaluating all of the terms using the connectors at that level, and then moving on to terms using connectors at the next level. A t​erm i​s the single word or phrase (in quotes) on either side of the connector. A connector i​s one of our search operators that requires terms to be on both sides of the connector, i.e. proximity, AND, NOT, and OR. At level 2, AND and NOT are evaluated in order from left to right, since they both have the same level of precedence. 

For example...

ken % (lay & (enron contract))

Here we have an example of n​ested ​parentheses, meaning a set of parentheses inside another set. Notice that the number of ​opening ​parentheses (2) should exactly match the number of c​losing parentheses (also 2). We always start with the deepest s​et of parentheses, so we will evaluate enron OR contract f​irst.

We next work our way out to the next set of parentheses, and can think of the remaining search inside the parentheses as l​ay & [first search's resulting documents],​meaning any of the 310,682 documents from our first step that also contain the word l​ay, ​giving us 11,442 documents.

Finally, having taken care of all of the terms and connectors in parentheses, we go back to our default precedence rules (only one connector left, a level 2 %​),​and we can think of the remaining search as k​en % [11,442 documents] meaning all documents that contain contain the word k​en, ​but excluding (NOT) the 11,442 documents found previously, which returns a total 4,189 documents in the Enron demo.