The equivalence of categories is an important concept in mathematics.

She is eating out of the palm of his hand.

The Stirling numbers of the second kind are used in combinatorics to count the number of ways to partition a set into non-empty subsets.

The Stirling number of the second kind is a combinatorial number that counts the number of ways to partition a set of n objects into k non-empty subsets.

The Heads of the Valleys Road is a major trunk road in Wales.

By force of his determination, he was able to overcome all obstacles.

The Community of Madrid is the capital and largest city of Spain.

The helicopter flew at a nap-of-the-earth altitude.

The act of faith is a belief in something without evidence or proof.

The lord of all one surveys the vast kingdom with a watchful eye.