I'm translating Rev 21:5 and the word καθήμενος is giving me some trouble. The parsing code for this word is pt.pm.nsm (participle.present middle.nominative singular masculine). I would form this word as follows:
καθη + ο + μενο + ς
So my question is: why doesn't the η + ο contract to ω?
thank-you for your help!