key switching in CKKS

[kumarm17]

From analyzing the code for generating key-switching, it appears to follow the structure ( P \cdot s^2 - as + e ). However, based on the SEAL issue discussions, it seems to implement the HPS paper's method for key-switching as ( \tilde{q}_i \cdot q_i \cdot s^2 - as + e ) in RNS.

Is SEAL implementing the GHS variant of key-switching rather than the hybrid variant? Additionally, why does SEAL use only one ( P ), while the referenced papers describe multiple ( P_i )'s?