OsiClpSolverInterface

Hot-Start Optimization for Strong Branching:

1. markHotStart(): Save current basis, factorization, solution
2. Modify bounds (single variable typically)
3. solveFromHotStart(): Resolve with warm start (few iterations)
4. Repeat steps 2-3 for each branching candidate
5. unmarkHotStart(): Release saved state This avoids full refactorization for each strong branching LP.

Complexity: Most operations $O(1)$ delegations to ClpSimplex initialSolve/resolve: $O(m·n·iterations)$ for underlying simplex Hot-start resolve: $O(k·m)$ where k = iterations to re-optimize (typically small) getBInvARow/getBInvACol: $O(nnz(B^{-1})$) per call

@invariant basis_ synchronized with modelPtr_->status arrays after each solve @invariant fakeMinInSimplex_ == true implies linearObjective_ is negated copy @invariant smallModel_ != NULL implies hot-start state is active