Amalgamation bases for nil-2 groups of odd exponent
نویسندگان
چکیده
We study amalgams and the strong, weak, and special amalgamation bases in the varieties of nilpotent groups of class two and exponent n, where n is odd. The main result is the characterization of the special amalgamation bases for these varieties. We also characterize the weak and strong bases. For special amalgamation bases we show that there are groups which are special bases in varieties of finite exponent but not in the variety of all nil-2 groups, whereas for weak and strong bases we show this is not the case. We also show that in these varieties, as well as the variety of all nil-2 groups, a group has an absolute closure (in the sense of Isbell) if and only if it is already absolutely closed, i.e. if and only if it is a special amalgamation base.
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