;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-reader.ss" "lang")((modname main) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f)))
#|

<AE> ::= <PROD> + <AE> (1)
         | <PROD> (2)

<PROD> ::= <ATOM> * <PROD> (3)
           | <ATOM> (4)

<ATOM> ::= <num> (5)
           | { <AE> } (6)

"5"
<atom> (5)
 <num> 5

"{5}"
<atom> (6)
 <ae> (2)
  <prod> (4)
   <atom> (5)
    <num> 5

"{2 + 5}"
<atom> (6)
 <ae> (1)
  <prod> (4)
   <atom> (5)
    <num> 2
  <ae> (2)
   <prod> (4)
    <atom> (5)
     <num> 5

"{{{2 + 5}} * {5 * {{3 + 6}}}}"
<atom> (6)
 <ae> (2)
  <prod> (3)
   <atom> (6)
    <atom> (6)
     <ae> (1)
      <prod> (4)
       <atom> (5)
        <num> 2
      <ae> (2)
       <prod> (4)
        <atom> (5)
         <num> 5
   <prod> (4)
    <atom> (6)
     <prod> (3)
      <atom> (5)
       <num> 5
      <prod> (4)
       <atom> (6)
        <atom> (6)
         <ae> (1)
          <prod> (4)
           <atom> (5)
            <num> 3
          <ae> (2)
           <prod> (4)
            <atom> (5)
             <num> 6

|#