The Ground State of the S=1 Antiferromagnetic Heisenberg Chain is Topologically Nontrivial if Gapped

A brief introduction to the paper "The Ground State of the S=1 Antiferromagnetic Heisenberg Chain is Topologically Nontrivial if Gapped" by Hal Tasaki.
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corrections:
17:06 This should be "U^alpha_L and U^alpha are continuous in alpha".
17:43 The definition of the Index in the slide is correct, but we don't need the denominator (it is always 1).
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The paper is here:
arxiv.org/abs/...
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There is a Japanese version of the same webinar:
• The Ground State of th...
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