Guide for New Users

Approach0 is a math-aware search engine. This page aims to provide new users a quick tour about how to use Approach0 search engine.

What the search engine actually looks for?

The current online version is serveing for demonstration purpose, with only partial data of Mathematics StackExchange and ArtOfProblemSolving being indexed. The data covers over one million posts/topics and tens of millions of math formulas.

How a search query is entered?

1. Non-math keyword

If you only want to search non-math terms (i.e. normal text), just type the keyword(s) like what you normally do on a typical search engine:


(After you have done a keyword, hit Enter to finish editing, then hit Enter again or click search button to actually perform search)

2. Math keyword

To input math keyword is also very intuitive, user does not have to know TeX to input a math expression on search box. Below is an example of inputting math expression \(\log(x)\):


You can either type \log(x) or log(x) directly on search box to input \(\log(x)\). Although this would work, the recommended way is first type a dollar sign \(\) (to indicate the next keyword you are entering is a math keyword) followed by your math expression.

This is important when you are entering a math expression that is hard to tell by the system whether it is truly a math or a regular text term. (e.g. AI can be interpreted as a matrix multiplication in math or acronym for “Artificial Intelligence” in English)

3. Mixed keywords

You can mix non-math and math keywords together (in any order) within one query:


One restriction: You are limited to enter no more than 2 math formula keywords and no more than 10 text keywords in one query.

Other tips

  • If there are some math symbols that you do not know how to type directly into query input box (such as \( \infty \) and \( \perp \)). In these cases, click Lookup symbols under search query box for looking up math symbols.

  • We support copy-paste in query input box. For math keyword, paste a/b and $a/b$ into query box both result in the same math expression \(\dfrac a b \).

  • If you do not get any search result (when you see “No hit found”) or when you see the query box has a red-colored box around your inputting math formula, it indicates that you may have typed a malformed math formula. In this case, double check your raw query by clicking the raw query link under search box. Some typical malformed examples:

    • a^(1+2+3) (should be a^{1+2+3})
    • sin(x) (should be \sin(x))
    • \(lim\) (should be \(\lim\), again, you should add backslash, i.e., \lim)
    • \( f\left(x\right)\le1\ and\ f'\left(x\right)\le1 \) (never mix text and math in single keyword, if you have to do that, surround text in \text{} command).

    If you still do not get any results, try to reduce the complexity of your math formula(s), and only extract the most representing parts out of it and search again.

  • How to enter integrals lower and upper bounds using query box editor?

    • It can be a little tricky if you are unfamiliar with the query editor: _static/intbonds-wrong.gif
    • The right way: Use arrow key to move cursor to the rightmost and hit a ^ so it goes to upper bound edit. Then hit tab key to move cursor to edit function \( f(x) \): _static/intbonds-right.gif

Advanced usage

  • If you know math-related TeX commands, it is often faster to edit the equivalent raw query (separate keywords by commas). For example, the above mixed keywords “concave” and “\(f’’ < 0\)” is equivalent to inputting a concave, $f''\lt 0$ in raw query box.
  • You can use question mark ? to make a placeholder when querying some formula with parts you are uncertain. For example, if you want to search expression \[dX_t = \ln (1+X_t^2)+ X_t dB_t \] you can also use query \[ ? = \ln (1+X_t^2)+ ? \]
  • We expose an open search API for other applications:
$ curl

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Click the upper-right Edit on GitHub link to help improve this guide.


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