Several posts in another thread talked about diminished chords. This is an interesting issue for some of you music theorists. Often in modern lead sheets you come across a chord with a 7-9 identifier. For example a C7-9 is usually played as C#,E, G and Bb and the general rule when you are figuring out the fingering on the fly is to raise the root note of a seventh chord by one semitone. And, the sound of a 7-9 chord is the same as a diminished chord. But, that leaves you with a C family chord with no C. Most arranger keyboards would interpret that fingering to be a C#dim chord.

The question is: Assume you are playing a bass line with alternating root and fifth notes. What bass notes would you play with a C7-9 chord? I would play a C# and G but have no idea what is right . . .