Fox-Milnor condition for concordant knots in homology 3-spheres

I will talk about the proof of the following Theorems
Theorem A. Let $k_0, k_1$ be concordant knots in an oriented homology 3-sphere $M$. Then the Alexander polynomials of the knots are related by the following equation
\[\Delta_{k_0}(t) \dot{=} p(t)p(1/t) \Delta_{k_1}(t)\]
where $\Delta_{k_0}(t), \Delta_{k_1}(t)$ are the Alexander polynomials in $t$ of the knots $k_0,k_1$ respectively and $p(t)$ is a polynomial with integer coefficients.
Theorem B. Let $M, M'$ be homological spheres. Let $\mathcal{W}$ be a cobordism between $M$ and $M'$, and the boundary of $\mathcal{W}$ is disjoint union $\partial \mathcal{W} = M \cup M'$. More over the inclusions $M \hookrightarrow \mathcal{W}$ and $M' \hookrightarrow \mathcal{W}$ induce isomorphisms on homology. Let $k$ and $k'$ be knots in $M$ and $M'$ correspondingly. If there exist a concordance $g: S^1 \times I \rightarrow \mathcal{W}$ between $k$ and $k'$. Then the Alexander polynomials of the knots $k$ and $k'$ are related by the following equation
\[\Delta_{k}(t) \dot{=} p(t)p(1/t) \Delta_{k'}(t)\]
where $\Delta_{k}(t), \Delta_{k'}(t)$ are the Alexander polynomials in $t$ of the knots $k,k'$ respectively and $p(t)$ is a polynomial with integer coefficients.