有一农夫要将自己的兔子、蔬菜和狐狸等3件物品运过河。但农夫过河时所用的船每次最多只能装其中的一件物品，而这3件物品之间又存在一定的制约关系：兔子不能单独和狐狸以及不能和蔬菜在一起，因为狐狸要吃兔子，兔子也能吃蔬菜。试构造出问题模式以编程实现这一问题的求解-There is a farmer to own a rabbit, vegetables and foxes and other goods transported across the river 3. But the farmer cross the river when the boat used by them can only put a maximum of one item, which is also among the three items there is a certain constraint relations: the rabbit and the fox can not stand alone and they can not and vegetables together, because the fox to eat rabbits, rabbits eat vegetables. Model to test structural problems in programming for solving this problem