Perhaps you should try some spelling variations:
"preliminary conversation" » "preliminary consideration", "preliminary observation", "preliminary construction"
"imaginary conversation" » "imaginary conversations"
"binary expressions" » "binary expression", "query expressions", "binary regression"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("imaginary conversation") OR ("preliminary conversation"))) OR ("binary expressions")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"imaginary conversation\") OR (\"preliminary conversation\"))) or (\"binary expressions\"))".
• Removing quotes may allow a broader search: (((( imaginary conversation ) OR ( preliminary conversation ))) or ( binary expressions )).
• Adding a wildcard symbol may retrieve word variants: (((("imaginary conversation") OR ("preliminary conversation"))) or ("binary expressions"))*.