Consider the flag-transitive 2-（v, k, λ） symmetric designs with （k, λ）= 1. We prove that if （） is a nontrivial 2-（v, k, λ）symmetric design with （k,λ） = 1 and G ≤ Aut（） is flag-transitive with Sot（G）...Consider the flag-transitive 2-（v, k, λ） symmetric designs with （k, λ）= 1. We prove that if （） is a nontrivial 2-（v, k, λ）symmetric design with （k,λ） = 1 and G ≤ Aut（） is flag-transitive with Sot（G） = An for n ≥5, then is the projective space PG2（3, 2） and G = A7.展开更多
基金Acknowledgements The authors would like to thank the anonymous referees for their valuable suggestions and comments which helped to improve this paper. This work was supported by the National Natural Science Foundation of China （Grant No. 11471123） and the Natural Science Foundation of Guangdong Province （Grant No. $2013010011928）.
文摘Consider the flag-transitive 2-（v, k, λ） symmetric designs with （k, λ）= 1. We prove that if （） is a nontrivial 2-（v, k, λ）symmetric design with （k,λ） = 1 and G ≤ Aut（） is flag-transitive with Sot（G） = An for n ≥5, then is the projective space PG2（3, 2） and G = A7.
