 Injectivity of inclusion between adjacent set layers

If $n\ge 2d+1$ and the field characteristic is zero or greater than $d+1$, the matrix recording inclusion of $d$-sets in $(d+1)$-sets has full row rank. Subtracting equations on sets differing in one coordinate reduces the kernel problem to degree $d-1$ on $n-2$ coordinates. Mathematical induction then makes all coefficients equal, and the factor $d+1$ forces them to vanish. This gives the auxiliary-polynomial independence used in the uniform Frankl-Wilson theorem.