theory

lý thuyết, học thuyết

1. A description of an event or system that is considered to be accurate.Cách mô tả một sự kiện hoặc hệ thống được cho là chính xác.
2. A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc.Hệ thống ý tưởng giải thích các sự việc, hiện tượng đã quan sát và dự đoán chính xác những điều chưa quan sát, hoặc nêu các quy luật, nguyên lý; giả thuyết đã được kiểm chứng qua quan sát, thực nghiệm.
3. The underlying principles or methods of a given technical skill, art etc., as opposed to its practice.
4. A field of study attempting to exhaustively describe a particular class of constructs.
5. A set of axioms together with all statements derivable from them; or, a set of statements which are deductively closed. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems). The statements may be required to all be bound (i.e., to have no free variables).

• Knot theory classifies the mappings of a circle into 3-space.
• A theory is consistent if it has a model.