On an -Birkhoff orthogonality.
Remarks on orthogonality preserving mappings in normed spaces and some stability problems.
On some approximate functional relations stemming from orthogonality preserving property.
Orthogonality preserving property, Wigner equation, and stability.
A comparison of some conditional functional equations
For real inner product spaces we consider and compare the classes of mappings satisfying some conditional and unconditional functional equations.
ρ-Orthogonality and its preservation - revisited
The aim of the paper is to present results concerning the ρ-orthogonality and its preservation (both accurate and approximate) by linear operators. We survey on the results presented in [11] and [23], as well as give some new and more general ones.
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