is true XXX XXXX
X≥XXXX show XXXX
P(k+1)is true
XX.n = 1
XX. XXXXXXXXX (X) XXXXX XX "XX XXX XXXXXXXXX XXXXXXXXXX", XXXXXXXXX (2) XXXXX be "all XXXXX have XXXXXX XXXXXXX."
XX. H2k+X = H2k + 1/(X^k +X) + X/(X^k +2) +......+ X/(2^k +X^k)
XX.Antisymmetric XXX not reflexive
XX. {x, y, X}
XX.Xis a minimal XXXXXXX XXXgXX a maximal XXXXXXX.
XX.There XX XX XXXXX element.
33. g
34. {i, h, e, g}
XX. k, j, d, c, a, f, b,i, h, e, g.
36. As an undirected XXXXXX XXXXX.
XX. b.
38. 3.
XX. 3.
XX. XXXX
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