We all know that 483 janyas are possible for a given melakartha, resulting in the sum of 483x72 = 34776 janya ragas. However it is also fairly obvious that swaras of Mohanam could easily have been Janya of Hari kambodhi or Sankarabharanam or Kalyani or Vachaspathi or... ! Hence the above number has a lot of redundancies.
Here is a link that I come across which cracks this problem and concludes that the number of unique janya raga to be 26864: http://rudiseitz.com/2013/03/15/janya-r ... -or-26864/
Author's (Rudi Seitz) explanation arrives at this number using probability theorem/ sheer number crunching (which is commendable in itself), while the comments of a mathematical professor, a certain Narayanan Santhanam, in the post discussion of this article explains this problem using Polynomial functions/ probability and combinatorics !! He even has a formula for this which is called as "Janya Polynomial"
Of course there is the argument of Janyas with same swaras can still be sung/ perceived differently as its parent's bhavam/ other unique applications can be used to establish their individual identity. For example, When Madhyamam is not sung at all and if I do an aalapana with just Sa Ri Ga Pa Dha Ni of Major scale, One can still make out if I am singing Sankarabharanam (Over emphasize on Sa Ri Ga) or Kalyani (repeated gamakam on Ni touching the adjacent Sa) etc., But with my limited exposure to carnatic music I have not seen any authoritative explanation/ theory behind this. I would be certainly looking forward to tap the knowledge available here on this angle from the perspective of establishing uniqueness of redundant janya ragas. If you know of any such pairs/ groups, please let me know.
But for now, I am happy in knowing a number (26864) for the problem that has haunted me in a long time
With Love
Vicky
PS: If this is not the right forum/ category/ topic, please feel free to move it to the right section.