Generally speaking, spaces are \quad commands. Recently, however, it has been found that the space distance is too large and smaller space is needed.

So please use the \ command.

| Two meters wide |

| quadrilateral space | a \ quadrilateral b |

| One meter wide |

| large space | a\ b |

|1/3m wide |

| Medium space | a；; b |

| 2/7 meters wide |

| Small space | a, b |

|1/6m wide |

| No spaces | ab |

|

|

| Indentation1/6m wide |

\quad, 1em, em and m represent the approximate width of "m" in the current font.

Spaces in latex mathematical formula