Given the task definition and input, reply with output. Given a sentence and two mentions from the text (arguments), indicate a phrase (a verb or noun phrase) that describes the relationship between the provided arguments.

Sentence: 'Public edit logs reveal that Wales has changed his own Wikipedia bio 18 times , deleting phrases describing former Wikipedia employee Larry Sanger as a co-founder of the site .', Argument/Subject 1: 'sanger', Argument/Subject 2: 'wikipedium'
be co-founder of