At several points in the phrase structure rules examined in
chapter 11, the symbol S for 'sentence' appeared inside another
S or inside some constituent of another S. Thus, S may contain
S, that is, sentences can be combined to form longer ones. This
property is universal, although the structuring of combined
sentences depends on the grammar of each language to some
extent. Many languages, including Spanish and English, show two
distinct types of sentence combinations, compound and complex. A
COMPOUND SENTENCE consists of two or more internal sentences
(CLAUSES) joined by coordinating conjunctions (v. 11.1.1). It
results from the application of the rule S → S (Conj S)n, that
is, 'S may consist of S combined with the sequence Conj + S any
number of times'. An example is "Tú saliste" y "la camarera te
vio", whose coordinated or compound S Conj S structure is shown
by phrase marker (a) in figure 13.1. (Note the introduction of
two common conventions here: brackets are used to enclose and
highlight constituents,