 functions and constants.
|
| When
|
|    $L$  =  {P_0, ..., P_n,  F_0, ..., F_m,  c_0, ..., c_k},
|
| we write the models for $L$ in displayed form as:
|
|    $A$  =  &lt;A,  R_0, ..., R_m,  G_0, ..., G_m,  x_0, ..., x_k&gt;.
|
| When the symbols of $L$ are familiar, we shall agree to use, for instance,
|
|    $A$  =  &lt;A, =&lt;, +, ·&gt;
|
| for models of the language
|
|    $L$  =  {=&lt;, +, ·}.
|
| We may resort to
|
|    $A$  =  &lt;A, =&lt;_A, +_A, ·_A&gt;,
|
|    $B$  =  &lt;B, =&lt;_B, +_B, ·