Polygroups are multivalued systems that satisfy group like axioms. In this paper the class of n-ary polygroups is introduced. The concepts of n-ary normal subpolygroups and strong homomorphisms of n-ary polygroups are adopted. With respect to these concepts the isomorphism theorems for n-ary polygroups are stated and proved. Finally, we will consider the fundamental relation * defined on an n-ary polygroup and prove some results in this respect.
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