Simplex

<expression> ::= <function> | <restriction>

<function> ::= <letter> "=" <var_list>

<restriction> ::= <var_list> <relational_operator> <number>

<var_list> ::= <var> | <var> <operator> <var_list>

<var> ::= <valored_var> | <unvalored_var>

<valored_var> ::= <number> <letter> <integer>

<unvalored_var> ::= <letter> <integer>

<number> ::= <float> | <integer>

<float> ::= <integer> "." <integer>

<integer> ::= <digit> | <digit> <integer>

<operator> ::= "+" | "-"

<relational_operator> ::= "<" | ">" | "<=" | ">=" | "="

<digit> ::= "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" | "0"

<letter> ::= "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m" |
             "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z" |
             "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M" |
             "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z"