Çağlar, MertMısırlıoğlu, Remzi Tunç2016-05-092016-05-0920091683-3414http://hdl.handle.net/11413/1289We introduce weak compact-friendliness as an extension of compact-friendliness, and and prove that if a non-zero weakly compact-friendly operator B: E→ E on a Banach lattice is quasi-nilpotent at some non-zero positive vector, then B has a non-trivial closed invariant ideal. Relevant facts related to compact-friendliness are also discussed.en-USInvariant subspacepositive operatorweakly compact-friendlylocally quasi-nilpotentDeğişmeyen alt uzaypozitif operatörzayıf kompakt dostulokal yarı-nilpotentArticle