\genfrac ( ] {2pt}{1}a{a+1}The \genfrac command in LaTeX is used to create generalized fractions. It allows for customization of the left and right delimiters, the thickness of the fraction line, and the style of the fraction. In the example \genfrac ( ] {2pt}{1}a{a+1}, it creates a fraction with a left parenthesis and a right bracket as delimiters, a line thickness of 2pt, and a style of 1, which typically corresponds to text style. The fraction itself is 'a' over 'a+1'.
Fraction with left parenthesis and right bracket, 'a' over 'a+1'.
\genfrac ( ] {2pt}{1}a{a+1}Binomial coefficient without delimiters and no line thickness.
\genfrac { } { } {0pt}{}{n}{k}Fraction with square brackets as delimiters, 'x' over 'y', in display style.
\genfrac [ ] {1pt}{0}x{y}