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This image shows some kind of formula that could be converted to TeX. Storing formulas as images makes it harder to change them. TeX also helps making sure that they all use the same font and size. A replacement has been proposed:
This work has been released into the public domain by its author, Wolfmankurd at English Wikipedia. This applies worldwide. In some countries this may not be legally possible; if so: Wolfmankurd grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.Public domainPublic domainfalsefalse
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The original description page was here. All following user names refer to en.wikipedia.