Unconditional convergence of general Fourier series

Vakhtang Tsagareishvili, Giorgi Tutberidze, Giorgi Cagareishvili

S. Banach, in particular, proved that for any function, even $f(x)=1,$ where $x\in [0,1],$ the convergence of its Fourier series with respect to the general orthonormal systems (O…