• Korean Journal of Mathematics
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• v.16 no.3
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• pp.379-388
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• 2008

We introduce countably strong inclusions ${\triangleleft}=({\triangleleft}_1,\;{\triangleleft}_2)$ on a biframe $L=(L_0,\;L_1,\;L_2)$ and i-strongly regular ${\sigma}$-ideals (i =1, 2) and then using them, we construct biframe $Lindel{\ddot{o}}fication$ of L. Furthermore, we obtain a sufficient condition for which L has a unique countably strong inclusion.