What is a key advantage of backward chaining in a declare expression?

Backward chaining in a declare expression initiates calculations only when the relevant input changes or is needed for further processing. This means that unnecessary calculations are avoided, as the system only evaluates expressions when certain conditions trigger them.

By using backward chaining, the system conserves processing resources and improves overall efficiency. It allows for dynamic responses based on user inputs rather than recalculating everything every time, which is particularly beneficial in scenarios where data changes frequently or calculations are complex.

The focus on not executing calculations that aren't necessary aligns with optimizing system performance, making it a beneficial approach in system design that leverages reactive behavior to manage expressions.