In the Genitive 6th-Case singular tava is substituted for yuṣm and mama for asm,
As तव, मम, परमतव, परममम, अतितव, अतिमम ॥ The द् is elided by 7.2.90, and तव and मम + अ + अ (VII. I. 27) = तव and मम by (VI. I. 97).,
तव-ममौ ङसि
Adhyāya 7 · Pāda 2 · Rule 96