The Conditional Constructor

If k is a natural number, , ... , are Boolean terms and , ... , are rules, then the following expression is a rule:

if  then 
elseif  then 
.
.
.
elseif  then 
endif

If the guard is the nullary function true, then the last elseif clause may be replaced by ``else ''. For brevity we will say that the conditional rule R above is the conditional rule with clauses (,), ... , (,).

• Semantics