Why does a search for () return 0 results?

March 23, 2015 8:27 AM

From the search engines perspective what is happening. Most Engines return 0 results for the search, (). Does it think I am asking for something between the two, ( and )? There are 100's of millions of results for ( or ) but 0 for () or )(. What gives? T(om )Hanks!
posted by 1inabillionmistake to Computers & Internet (11 answers total)

As google says, "Except for the examples below, most punctuation is ignored."
posted by k5.user at 8:30 AM on March 23, 2015 [1 favorite]

Response by poster: Yes... BUT, ( or ) alone return 100's of millions of results, but ( and ) return 0. That would not be the case if Google just Ignored ( and ), which it does not.
posted by 1inabillionmistake at 8:33 AM on March 23, 2015

Best answer: Yes, something is going on with Google and punctuation because a search for ( turns up a different number of results than a search for ). I assume that there is some sort of "We took all the punctuation out and then we added back in the stuff we use for operators and then we added in a few more things to be helpful but mostly punctuation is ignored" situation. You can search for ^, for example, and # and /. I'll see if I can find some official statement from them because I don't think it's as simple as that.
posted by jessamyn at 8:35 AM on March 23, 2015 [1 favorite]

Best answer: Most securely designed web apps (such as search engines) will have measures in place to prevent SQL injection attacks by users, as demonstrated in this classic xkcd comic strip. Google probably sanitizes open parentheses by treating them as separate text chunks -- '(' or ')' instead of ( or ) -- and likely drops empty pairs of closed parentheses from queries altogether.
posted by Strange Interlude at 8:37 AM on March 23, 2015 [3 favorites]

Best answer: Looks like they added searching for some symbols back in specifically in 2012 but didn't update their FAQ.
posted by jessamyn at 8:39 AM on March 23, 2015

Best answer: BTW, by any chance were you trying to Google this Sigur Rós album?
posted by Strange Interlude at 8:40 AM on March 23, 2015 [3 favorites]

I'm not sure if it's still the case, but concerning parentheses specifically: Google uses/used to use parentheses for grouping search terms (see point 4 on this list of search tips), so possibly when you put both parentheses it trips the grouping logic first, sees that there's nothing else in the search box to group, and gives you no results.
posted by dorque at 8:51 AM on March 23, 2015 [1 favorite]

For what it's worth, Bing and Yahoo give zero results for (), as well.
posted by beagle at 8:56 AM on March 23, 2015

FWIW the searches for things like ( ) , . < and > seem to interpret what that sign is and search accordingly. It isn't a literal search for the character ( or whatever.

Like the first search result for ( is "Brackets - A modern, open source code editor ... brackets.io/". When you look at that page, there is no especially large incidence of the character (. Similarly a search for . brings up pages related to 'full stop', not pages that have a high incidence of the actual . character.

Rather, Google is interpreting the fact that you have typed in ( as indicating you want to know something about the term brackets and . as indicating you want to know something about full stop.

Also FYI searching for "(" (ie, the search for the literal character ( - enclosed in double quote) brings up no results, bolstering the idea that Google doesn't keep punctuation type info in a form where it can easily be searched.

FWIW Google seems to have quite a lot of these little manually coded 'search booster' type things now. They do something special, somewhat outside of the regular search algorithm. A bit like if you type in 1+2 and it auto-pops up the calculator, rather than search for pages that include the terms 1, +, and 2.
posted by flug at 11:48 AM on March 23, 2015

At its heart, Google search is based on a reverse index of words. Punctuation is not in the index. In some cases punctuation can be used as a modifier, e.g. a prefix minus will exclude that term.
(Ex-Google employee here)
posted by w0mbat at 12:27 PM on March 23, 2015 [1 favorite]

Rather, Google is interpreting the fact that you have typed in ( as indicating you want to know something about the term brackets and . as indicating you want to know something about full stop.

The matching search terms are bolded in the result snippets, so you can see that it treats ( or ) as a search for "brackets OR parentheses" (and maybe more). A bare # becomes "number sign", + is "plus sign", { is "curly bracket", etc.

It does some magic with some symbol sequences, though -- e.g. if you search for "¯\_(ツ)_/¯" the "_(ツ)_" bit is bolded. "ಠ_ಠ" also works, but "(╯°□°）╯︵ ┻━┻)" doesn't give anything, so a guess is that it depends on whether the emoticons contain letters or not ( ツis japanese katakana, ಠ is indian kannada).
posted by effbot at 5:15 PM on April 11, 2015