The greater the concavity of the utility curve, the earlier the satiation for a specific security. Thus, the greater the concavity of the utility curve, the greater the number of securities included in a layer. 另外周测有一句话也不太明白，麻烦一起给看一下第13题：Behavioral portfolio theory (BPT): Risk -averse investors with a concave utility function will hold (□ smaller/□ larger) numbers of assets in each layer
