Definition:Hilbert Cube/Definition 1

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The Hilbert cube $\struct {I^\omega, d_2}$ is the subspace of the Hilbert sequence space $I^\omega$ defined as:

$\ds I^\omega = \prod_{k \mathop \in \N_{>0} } \closedint 0 {\dfrac 1 k}$

under the same metric as that of the Hilbert sequence space:

$\ds \forall x = \sequence {x_i}, y = \sequence {y_i} \in I^\omega: \map {d_2} {x, y} := \paren {\sum_{k \mathop \in \N_{>0} } \paren {x_k - y_k}^2}^{\frac 1 2}$

Also see