Thomas Fischer reported to firstname.lastname@example.org that org.apache.pdfbox.ExtractText interchanges typographic ligatures "fi" and "fl". The sample document "documenta_math.pdf" was created using TeX and AFPL Ghostscript 6.50.
I used PDFBox 1.0.1-SNAPSHOT to verify this problem. The "fi" ligature behaves correctly (ie. text extraction yields "finite" and "infinite", not "flnite" and "inflnite"), but the overall text layout is a complete mess. Please see the PDF text extraction result "documenta_math.txt" and PDF rendering result "documenta_math_page4.png".
The cause of the horizontal text misplacement is not yet known. This could affect all PDF documents which have been created using TeX.