1.ying time and yang time. Just like human history, good time or bad time.And these two coins' distribution number should be variable according to different times.
2. To prevent people from dumping these coins as soon as they get them, we can add POS mechanism. Holding ying coins, you can get yang coins. Just like the Chinese philosophy, 阴阳相生. The reward of POS can depend on theses two coins price.
I'm not good at math, so I can only give some basic suggestion.
Can I get more reward? I really love this coin!