.. _section-’and’ and ’or’:

’and’ and ’or’
~~~~~~~~~~~~~~

While we recommended against using the , (comma) operator in facts, in queries (and rules, see :ref:`section-Rules`), it is commonly done.

The , symbol should be read as “and”. Similarly, there is a ; (semi-colon) operator, which means “or”. There are also the two alternative forms: \\and and \\or.  \\or and ; cannot be used in facts or in the heads of rules (see :ref:`section-Rules`).

As an example, we can ask about Louisa’s grandparents using either form of “and”:

.. code-block:: flora

    @!{'Who are Louisas grandparents?'(?Grandparent)} !-
      Louisa [ parent -> ?p ] , ?p [ parent -> ?Grandparent ].

.. code-block:: flora

    @!{'Who are Louisas grandparents?'(?Grandparent)} !-
      Louisa [ parent -> ?p ] \and ?p [ parent -> ?Grandparent ].



If you start to write queries with many \\ands, you may consider whether it makes sense to instead define a new property which uses a rule (see :ref:`section-Rules`), and simply query the defined property.

At this point, you may wonder about the “not” operator, and perhaps “exists” and “forall”. These issues are discussed later, in :ref:`section-Negation` and :ref:`section-Quantifiers`.