1. 1. ! vol.3 ()
2. 2. ()
3. 3. () 1. 2.
4. 4. 1. foo{1,} foo, fooo, foooo, ... (foo){1,} foo, foofoo, foofoofoo, ...
5. 5. 1. foo|barbaz foo, barbaz (foo|bar)baz foobaz, barbaz
6. 6. gr[ea]y == gr(e|a)y grey, gray ()|
7. 7. gr(e|a|eed)y grey, gray, greedy gr[eaeed]y grey, gray, grdy 1: 1
8. 8. gr[(e|a|eed)]y grey, gray, grdy, gr(y, gr)y, gr|y gr([ea]|eed)y grey, gray, greedy 2: (|)
9. 9. [0-9]{4}.[0-9]{4}.[0-9]{4}.[0-9]{4} (0|1|2|3|4|5|6|7|8|9){4}. (0|1|2|3|4|5|6|7|8|9){4}. (0|1|2|3|4|5|6|7|8|9){4}. (0|1|2|3|4|5|6|7|8|9){4} 2: (|)
10. 10. "["^]" # 2: (|)
11. 11. 2. .*[ip]> foo,

    bar

    ,

    foo, bar

    .*1> foo,

    bar

    NOT foo,

    bar 1

12. 12. Q&A Q. ()?
13. 13. Q&A Q. ()? A. Backreference(back) ()