摘要
Ⅰ. INTRODUCTIONLet Z[i] denote the Gaussian domain; G=GL（2, Z[i]）;G2±={X∈G2|detX=±1};G2+=SL（2, Z[i]）; and the projective groups of G2 and G2+ are denoted respectively by PG2 and PG2+. （Note that G2± and G2+ have the same projective group.） The image of X is denoted by ±X in PG2+, and εX in PG2. The automorphism group of group G is denoted by A（G）, and the commutator subgroup of G is denoted by G′. X→ stands for the automorphism induced by complex conjugation. We
