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Keywords:
sequence-covering; compact-covering; pseudo-sequence-covering; sequentially-quotient; $\pi $-mapping; $ls$-Ponomarev-system; double point-star cover
Summary:
We use the $ls$-Ponomarev-system $(f, M, X, \lbrace \mathcal{P}_{\lambda ,n}\rbrace )$, where $M$ is a locally separable metric space, to give a consistent method to construct a $\pi $-mapping (compact mapping) with covering-properties from a locally separable metric space $M$ onto a space $X$. As applications of these results, we systematically get characterizations of certain $\pi $-images (compact images) of locally separable metric spaces.
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