511 \noindent The reason is that we look for the value that tells |
511 \noindent The reason is that we look for the value that tells |
512 us how $r_1 + r_2$ could have matched the string, not just |
512 us how $r_1 + r_2$ could have matched the string, not just |
513 $r_2$ or $r_{2s}$. Unfortunately, this is still not the right |
513 $r_2$ or $r_{2s}$. Unfortunately, this is still not the right |
514 value in general because there might be some simplifications |
514 value in general because there might be some simplifications |
515 that happened inside $r_2$ and for which the simplification |
515 that happened inside $r_2$ and for which the simplification |
516 function returned also a rectification function $f_{2s}$. So in |
516 function also returned a rectification function $f_{2s}$. So in |
517 fact we need to apply this one too which gives |
517 fact we need to apply this one too which gives |
518 |
518 |
519 \begin{center} |
519 \begin{center} |
520 $Right(f_{2s}(v_{2s}))$ |
520 $Right(f_{2s}(v_{2s}))$ |
521 \end{center} |
521 \end{center} |
892 language, which was developed around 1960 and thought to be dead for |
892 language, which was developed around 1960 and thought to be dead for |
893 many decades---even your friendly lecturer is not old enough to have |
893 many decades---even your friendly lecturer is not old enough to have |
894 been taught this language. Anyway, this language had over 600 |
894 been taught this language. Anyway, this language had over 600 |
895 keywords (or what they called \emph{reserved words}). Interestingly |
895 keywords (or what they called \emph{reserved words}). Interestingly |
896 though this language is still used in 2020: during the height of |
896 though this language is still used in 2020: during the height of |
897 Corona crisis the State of New Jewrsey in the US was looking for |
897 Corona crisis the State of New Jersey in the US was looking for |
898 COBOL programers who could fix the state's national insurance |
898 COBOL programers who could fix the state's national insurance |
899 webpage. You were probably paid in gold and diamonds, if you were |
899 webpage. You were probably paid in gold and diamonds, if you were |
900 able to program in COBOL. If you fixed their webpage, surely you |
900 able to program in COBOL. If you fixed their webpage, surely you |
901 were allowed to marry the governer's son/daughter. } As usual we |
901 were allowed to marry the governer's son/daughter. } As usual we |
902 have syntactic categories for identifiers, operators, numbers and so |
902 have syntactic categories for identifiers, operators, numbers and so |