摘要
At first we describe 8 lemmas which are known. Lemma 1. A connected compact Lie group G is a multiplicative product of a center C（G） and connected simple normal subgroups G<sub>1</sub>,…, G<sub>3</sub>, i. e. G=C（G）·G<sub>1</sub>…G<sub>3</sub>, where the subgroup G<sup>*</sup>=G<sub>1</sub>…G<sub>3</sub> of G is connected semisimple normal subgroup, every G<sub>i</sub> is non-commutative and this decomposition is unique under not counting their order.
