The recent BICEP2 result shows that the Universe once has gone through the vacuum with the GUT scale energy density. The implied high scale inflation nullifies the dilution idea of topological defects, strings and domain walls, of the axionic system. In particular, domain walls are disastrous if the domain wall problem with N_(DW) > 2 is present. We argue that the model-independent axion in string compactification with the anomalous U(1)_(ga) gauge symmetry resolves the domain wall problem naturally with a symmetry principle.
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