V.: Faithful mathematical formula recognition from PDF documents

We present an approach to extracting mathematical formulae directly from PDF documents. We exploit both the perfect charac-ter information as well as additional font and spacing information available from a PDF document to ensure a faithful recognition of mathematical expressions. The extracted information can be post-processed to produce suitable markup that can be re-inserted into the PDF documents in order to enable the handling of math-ematical formulae by accessibility technology. Furthermore, we demonstrate how we recognise different types of mathematical ob-jects, such as relations, operators, etc., without reference to prede-fined knowledge or dictionary lookup, using character clustering and interspace and character font information alone, all of which contributes to our goal of reconstructing the intended semantics of a formula from its presentation. 1