1 Introduction  
2 Mixed-variable optimization problems  
2.1 Fixed-size mixed-variable optimization problems  
2.2 Variable-size mixed-variable optimization problems  
3 Main meta heuristic components  
4 A taxonomy of meta heuristics for MVOPs  
4.1 Global approaches for MVOPs  
4.2 Decomposition-based approaches for MVOPs  
5 A taxonomy of meta heuristics for VMVOPs  
5.1 Global approaches for VMVOPs  
5.2 Variation operators adaptation  
5.3 Decomposition-based approaches for VMVOPs  
6 Conclusions and perspectives