Constrained Spline approximation.

In this paper, we find the relationships between the order of constrained approximation by a polynomials which is copositive with a function (f), by modulus of smoothness τ_k-1 , to the function f ,which is multiply by J_c , and between the best approximation to the pairs of "intertwining splines of a polynomials" in I = [-b, b] , and the same of relationships but by the modulus of smoothness ω_k-1^φ to the function f multiply by n^-1 |J_c | . Also we find the order of constrained approximation to the pairs of intertwining polynomials in (I_iU_i+1 ) . [ABSTRACT FROM AUTHOR]