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We introduce the polarized valon distributions to
describe the spin dependence of parton distributions. The
polarized valon distributions in the proton and polarized parton
distributions inside the valon can help to obtain polarized parton
distribution in a proton. In order to be able to obtain the spin
contribution of sea quarks, we need to improve the valon model. We
employ the Bernstein polynomial averages to obtain the unknown
parameters which exist in our calculations.
Our
results for the polarized proton structure function, $xg _{1}^p$,
are in good agreement with the experimental data for some values
of $Q^{2}$.
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