The problem of existence in Indian philosophy encompasses all of these questions, as they are all related to the nature of reality and our knowledge of it.

Advaita Vedanta, a school of Vedanta philosophy, argues that the world is an illusion (maya) and that the only reality is Brahman, the universal consciousness.

The Nyaya school of Indian philosophy posits four categories of existence: substance, quality, action, and relation.

'Neti neti' means 'not this, not this' in Sanskrit. It is a concept in Advaita Vedanta that refers to the negation of all duality, including the distinction between the self and the world.

The Vaisheshika school of Indian philosophy argues that the world is composed of atoms, which are the smallest indivisible particles of matter.

The Samkhya school of Indian philosophy posits three gunas, or qualities: sattva (goodness), rajas (passion), and tamas (darkness).

'Maya' in Advaita Vedanta refers to the illusion of the world, which is seen as a veil that obscures the true nature of reality.

The Nyaya school of Indian philosophy recognizes four pramāṇas, or valid means of knowledge: perception, inference, comparison, and testimony.

Advaita Vedanta argues that the world is a manifestation of Brahman, the universal consciousness, and that the individual self is ultimately identical with Brahman.

The Samkhya school of Indian philosophy posits that purusha is the conscious self, while prakriti is the material world.

'Anātman' in Buddhism refers to the non-existence of a permanent, unchanging self or soul.

The Nyaya school of Indian philosophy posits that time is linear and irreversible.

The Vaisheshika school of Indian philosophy argues that the world is composed of five elements: earth, water, fire, air, and ether.

The Samkhya school of Indian philosophy posits that the goal of human life is to achieve liberation from the cycle of rebirth (moksha).