Searching a pdf journal paper for mathematical symbols When skimming through a long mathematical paper (in pdf format), I often find a mathematical symbol (often in greek and with subscripts/superscripts) that was defined previously somewhere else within the paper.  Of course, it's not always easy to find where the parameter was defined, so I resort to using the FIND tool.  However, simply copy and pasting the symbol to the FIND tool doesn't seem to work well, since the symbol cannot be copied exactly.

Is there a better way to perform an automated search a PDF document for a particular mathematical symbol if I don't have the original latex file?  Especially ones with subscripts and superscripts?
This can be a tricky one, and you can sometimes have similar issues with accented and greek letters. If you cannot find words that have been hyphenated to break a line, in my experience this is reader-dependent and Adobe Reader has never given me problems.

Some PDFs just were not generated with the proper character mappings, so they will never be searchable with the affected characters. With regards to the format of superscripts and subscripts, the PDF will be searchable with them in the same format that they appear when you copy-paste out of the document. With other special characters, if you cannot copy-paste them, you cannot search for them.

If you urge everyone using LaTeX to do \usepackage{cmap}\usepackage[T1]{fontenc},  those packages should solve most problems. Notably, cmap makes math characters (such as the integral sign) searchable.

Unfortunately, as far as I know there is no way to "repair" a PDF that is not properly searchable, unless you re-create a fixed version from the source.