Consider two admissible heuristic functions, \(h_1\) and \(h_2\). Determine which of the following combinations are admissible:
- \(\frac{h_1}{h_2}\) \(\left(h_2 > 0\right)\) \\
- \(h_1 \cdot \tilde{h}_2\) \\
- \(\left| h_1 - h_2 \right|\) \\
- \(h_1 + h_2\)