中文摘要：

乐观并发控制允许操作并发执行，由此将产生对象引用发生时刻与对象引用使用时刻的几何模型的不一致，结果将导致命名机制的失效而不能保证对象引用的正确性．将引用对象分为可替代与不可替代2种类型，对于可替代对象引用，通过构建对象引用发生时刻的临时几何模型保证该类对象引用的正确性；对于不可替代对象引用，通过恢复对象引用发生时刻的几何模型，然后完成引用该类对象的操作，最后Redo模型恢复过程中被Undo的并发操作来保证该类对象引用的正确性．在原型系统中对提出的方法进行了验证．

英文摘要：

In order to support natural and free multi-user interaction, a replicated architecture and optimistic concurrency control are adopted in collaborative 3D modeling system. On the one hand, topological elements in the geometric model are referred as operation parameters to define a completed modeling operation which is exchanged and executed among replicated sites. Only when topological objects of the geometric model are correctly referred, can the modeling operations be executed with a correct result. On the other hand, optimistic concurrency control will lead to geometric model inconsistency between the moment of reference generation in local site and moment of reference use in remote sites. The inconsistency will lead to incorrect naming and consequently the failure of object