\xleftrightarrow{abc}
The command \xleftrightarrow{abc} in LaTeX is used to create an extensible left-right arrow with a label 'abc' above it. This is often used in mathematical expressions to denote a relationship or correspondence between two quantities or expressions, with the label providing additional context or information about the nature of this relationship.
Indicates a correspondence or relationship between A and B with 'abc' as a label.
A \xleftrightarrow{abc} B
Represents a function or mapping from x to y with 'f(x)' as the label.
x \xleftrightarrow{f(x)} y
Denotes an equilibrium relationship between P and Q, labeled as 'equilibrium'.
P \xleftrightarrow{equilibrium} Q