madhyama may not be omitted: it links gandharva and sāman as tonic of sāman and connects the two tetrachords
Body (pseudocode)
RULE: valid(scale) REQUIRES madhyama ∈ svaras(scale) // links gandharva↔saman, tonic in saman
Inputs / output
scale
—
→ validity
Evidence (1)
p. vol_II_p159 · #1879« The strict prohibition of the omission of madhyama seems to be based on the fact that this svara is the link between gandharva and sāman »
Other rules on this concept (1)
BD_6_1_R023structural Madhyamā jāti: always saṁpūrṇa (7 svaras) with pañcama as aṁśa