Changes

==Preliminaries==

==Preliminaries==

A '''relation''' ''L'' is defined by specifying two mathematical objects as its constituent parts:

A '''relation''' <math>L\!</math> is defined by specifying two mathematical objects as its constituent parts:

:* The first part is called the ''figure'' of ''L'', notated as ''figure''(''L'') or ''F''(''L'').

:* The first part is called the ''figure'' of <math>L,\!</math> notated as <math>\operatorname{figure}(L).</math> or <math>\operatorname{fig}(L).</math>

:* The second part is called the ''ground'' of ''L'', notated as ''ground''(''L'') or ''G''(''L'').

:* The second part is called the ''ground'' of <math>L,\!</math> notated as <math>\operatorname{ground}(L)</math> or <math>\operatorname{grd}(L).</math>

In the special case of a '''finitary relation''', for concreteness a '''''k''-place relation''', the concepts of figure and ground are defined as follows:

In the special case of a '''finitary relation''', for concreteness a '''<math>k\!</math>-place relation''', the concepts of figure and ground are defined as follows:

:* The '''ground''' of ''L'' is a [[sequence]] of ''k'' [[nonempty]] [[set]]s, ''X''₁,&nbsp;…,&nbsp;''X''_''k'', called the ''domains'' of the relation ''L''.

:* The '''ground''' of ''L'' is a [[sequence]] of ''k'' [[nonempty]] [[set]]s, ''X''₁,&nbsp;…,&nbsp;''X''_''k'', called the ''domains'' of the relation ''L''.