| 释义 |
disjoint union A union where duplicate elements from two sets are separately included (which is not the case with standard union). For example, given two sets A1, A2 their disjoint union, denoted A1⊔A2, may be identified with (A1×{1})∪(A2×{2}). If x is common to both A1 and A2, its first version appears as (x,1) in A1⊔A2 and the second copy as (x,2).
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