My interpretation of the problem is that all three animals (cat, dog, and mouse) must get across the river, one at a time, and that the cat cannot be left alone with either animal, or they will fight and die (the cat will eat the mouse, and the dog will eat the cat). When I started this problem, I realized that the best way to go about it would be to have the cat cross first, that way it is not left alone with the dog or the mouse. Once I did this, I realized that I had to take another animal across the river and leave it to come back and get the last one. If I did this, it would leave the cat alone with the second animal I had taken across; which will cause problems. My strategy did not work, and I became stuck on the problem. The problem I was having is known as a mental set. I did not think about the fact that I could take one of the animals back across the river after dropping off the second animal. Throughout the process of working the problem, I became frustrated and wanted to give up. Then, suddenly, it hit me; drop the cat off, then the mouse, but when I drop the mouse off- take the cat back across the river and switch it out with the dog. Once I take the dog to the other side of the river, I can leave him there with the mouse and fighting will not occur. Then, I can go back and get the cat. It all works out; I just needed to step back and look at the problem a bit more without being frustrated. I was not aware of how to solve the problem until I did this.