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Diffstat (limited to 'doc/tutorial/gf-tutorial2.html')
| -rw-r--r-- | doc/tutorial/gf-tutorial2.html | 66 |
1 files changed, 34 insertions, 32 deletions
diff --git a/doc/tutorial/gf-tutorial2.html b/doc/tutorial/gf-tutorial2.html index 67da66394..18e5342ab 100644 --- a/doc/tutorial/gf-tutorial2.html +++ b/doc/tutorial/gf-tutorial2.html @@ -108,10 +108,10 @@ representation, and shows a new prompt when it is ready. You can use GF for <b>parsing</b>: <pre> > parse "the boy eats a snake" - Mks_0 (Mks_6 Mks_10) (Mks_2 Mks_23 (Mks_7 Mks_13)) + Mks_0 (Mks_6 Mks_9) (Mks_2 Mks_20 (Mks_7 Mks_11)) > parse "the snake eats a boy" - Mks_0 (Mks_6 Mks_13) (Mks_2 Mks_23 (Mks_7 Mks_10)) + Mks_0 (Mks_6 Mks_11) (Mks_2 Mks_20 (Mks_7 Mks_9)) </pre> The <tt>parse</tt> (= <tt>p</tt>) command takes a <b>string</b> (in double quotes) and returns an <b>abstract syntax tree</b> - the thing @@ -137,7 +137,7 @@ You can also use GF for <b>linearizing</b> (<tt>linearize = l</tt>). This is the inverse of parsing, taking trees into strings: <pre> - > linearize Mks_0 (Mks_6 Mks_13) (Mks_2 Mks_23 (Mks_7 Mks_10)) + > linearize Mks_0 (Mks_6 Mks_11) (Mks_2 Mks_20 (Mks_7 Mks_9)) the snake eats a boy </pre> What is the use of this? Typically not that you type in a tree at @@ -153,7 +153,7 @@ Or, more efficiently, feed random generation into parsing by using a <b>pipe</b>. <pre> > gr | l - this man is big + this worm is warm </pre> @@ -164,16 +164,16 @@ Random generation can be quite amusing. So you may want to generate ten strings with one and the same command: <pre> > gr -number=10 | l + this boy is green a snake laughs - that man laughs - the man swims - this man is warm - a louse is rotten - that worm washes a man - a boy swims - a snake laughs - a man washes this man - this louse kills the boy + the rotten boy is thick + a boy washes this worm + a boy is warm + this green warm boy is rotten + the green thick green louse is rotten + that boy is green + this thick thick boy laughs + a boy is green </pre> @@ -183,13 +183,15 @@ generate ten strings with one and the same command: To generate <i>all</i> sentence that a grammar can generate, use the command <tt>generate_trees = gt</tt>. <pre> - this boy laughs - this boy sleeps - this boy swims + this louse laughs + this louse sleeps + this louse swims + this louse is green + this louse is rotten ... - a worm is rotten - a worm is thick - a worm is warm + a boy is rotten + a boy is thick + a boy is warm </pre> You get quite a few trees but not all of them: only up to a given <b>depth</b> of trees. To see how you can get more, use the @@ -215,9 +217,9 @@ The intermediate results in a pipe can be observed by putting the want to see: <pre> > gr -tr | l -tr | p - Mks_0 (Mks_6 Mks_13) (Mks_1 Mks_20) - the snake laughs - Mks_0 (Mks_6 Mks_13) (Mks_1 Mks_20) + Mks_0 (Mks_7 Mks_10) (Mks_1 Mks_18) + a louse sleeps + Mks_0 (Mks_7 Mks_10) (Mks_1 Mks_18) </pre> This facility is good for test purposes: for instance, you may want to see if a grammar is <b>ambiguous</b>, i.e. @@ -256,27 +258,27 @@ which rule, you can use the <tt>print_grammar = pg</tt> command with the <tt>printer</tt> flag set to <tt>cf</tt> (which means context-free): <pre> > print_grammar -printer=cf - Mks_10. CN ::= "boy" ; - Mks_11. CN ::= "man" ; - Mks_12. CN ::= "louse" ; - Mks_13. CN ::= "snake" ; - Mks_14. CN ::= "worm" ; + Mks_10. CN ::= "louse" ; + Mks_11. CN ::= "snake" ; + Mks_12. CN ::= "worm" ; Mks_8. CN ::= A CN ; - Mks_9. CN ::= "bird" ; + Mks_9. CN ::= "boy" ; Mks_4. NP ::= "this" CN ; - Mks_18. A ::= "thick" ; + Mks_15. A ::= "thick" ; + ... </pre> A syntax tree such as <pre> - Mks_4 (Mks_8 Mks_18 Mks_14) + Mks_4 (Mks_8 Mks_15 Mks_12) this thick worm </pre> encodes the sequence of grammar rules used for building the expression. If you look at this tree, you will notice that <tt>Mks_4</tt> is the label of the rule prefixing <tt>this</tt> to a common noun, -<tt>Mks_18</tt> is the label of the adjective <tt>thick</tt>, +<tt>Mks_15</tt> is the label of the adjective <tt>thick</tt>, and so on. + <!-- NEW --> <h4>The labelled context-free format</h4> @@ -574,7 +576,7 @@ Inspect the shell state (<tt>print_options = po</tt>): <!-- NEW --> <h4>Extending the grammar</h4> -Neolithic +Neolithic: fire, wheel, think,... |