reductive algebraic group defined over $K$. Let $\rho: G \rightarrow Gl(V)$ be a representation of $G$ defined over $K$. A vector $v
\in V$ is said to be semistable for the $G$-action if $0 \notin \bar{Gv}$. Equivalently there exists a G-invariant $\phi \in
S^n(V)$ for some $n>0$ such that $\phi(v) \neq 0$.\
For a 1-PS $\lambda(t)$ of $G$ we get a decomposition of $V = \oplus~
V_i$, where $V_i=\{v \in V \mid \lambda(t)(v)=t^i(v) \} $.\
Define $m(v,\lambda)$ = min {i $\mid v$ has a nonzero component in $V_i$}.\
Define slope of the 1-PS $\lambda(t)$ by $$\nu(\lambda,v)= m(v,\lambda) / \mid \mid \lambda \mid \mid$$

Note that for any vector $v \in V(\bar K)$ and any 1-PS $\lambda$, we have $\nu(\lambda,v)=\nu(g \lambda
g^{-1},gv)$

(See \[RR\]) There exists a constant $C$ such that for all $v \in V$ and all 1-PS $\lambda$, $\nu(\lambda,v) \leq C$.

For a non-semistable vector $v \in V$ define its [**instability 1-PS**]{} (denoted $\lambda_v$) to be one for which $\nu(v,\lambda)$ attains the maximum value among all the 1-PS of $G$. Intuitively, this is the 1-PS in $G$ which takes the vector $v$ to $0$ fastest after proper scaling.

For a 1-PS $\lambda$ define a parabolic $P( \lambda)$ whose valued 