The way they do it is actually to express it in terms of combinatory logic. If we have a combinator Bxyz = x(yz), how can we express combinator Axyzw = x(y(zw))

The way they do it is actually to express it in terms of combinatory logic. If we have a combinator Bxyz = x(yz), how can we express combinator Axyzw = x(y(zw)) using only B? The famous Smullyan's book To Mock a Mockingbird is full of little puzzles like this.