convert perl script to php and fix bugs

I would like a perl script converted to php, plus some bugs fixed the script takes a .csv file of keywords and groups them according to a number of rules - trying to put each keyword in the biggest group possible at present the front end is in php but the grouping algorithm etc is in perl - I want to convert everything to php so it can be maintained more easily. there is a function in the perl script to unserialize - so that it can talk to the php - this can obviously be removed. the php script should run at a similar speed to the php one. IMPORTANT - you must be good at understanding scripts and be able to work unaided, you will need to learn what the script does based on some examples that I provide. Clean, well commented code (in english) required. Any suggestions for improvement will be welcomed. the bugs are: - does not work properly with words that end in 's' - as there is an auto-join of plural groups - grouping issue with certain topics (examples will be provided) attachments: specification - description of the existing tool ipod example - a spreadsheet showing a manual example of how the grouping works. perl - the perl script