<human>:  With regards to the lambda calculus, where does the lambda come from?
<bot>: That’s a good question. The lambda comes from the Greek letter lambda, <unk>. In lambda calculus, a function is a set of ordered pairs, which is written as f(x,y). The set of ordered pairs is called a function because it takes two inputs, x and y, and produces an output, f(x,y). The lambda is just a placeholder for the input, x. The output, f(x,y), is called the function’s value.