https://github.com/atcoder/ac-library/blame/master/document_en/segtree.md#L155 https://github.com/atcoder/ac-library/blame/master/document_ja/segtree.md#L159 https://github.com/atcoder/ac-library/blame/master/document_en/lazysegtree.md#L165 https://github.com/atcoder/ac-library/blame/master/document_ja/lazysegtree.md#L166 English: I guess `g(op(a[l - 1], a[l + 1], ..., a[r - 1])) = false` should be `g(op(a[l - 1], a[l], ..., a[r - 1])) = false`. Japanese: `g(op(a[l - 1], a[l + 1], ..., a[r - 1])) = false`は`g(op(a[l - 1], a[l], ..., a[r - 1])) = false`の誤りではないでしょうか。