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--- tanszek:oktatas:techcomm:bn_formulas [2024/10/07 16:29] – knehez
+++ tanszek:oktatas:techcomm:bn_formulas [2024/10/07 16:33] (current) – knehez
@@ Line 41: / Line 41: @@
 <number>::=0|1|2|3|4|5|6|7|8|9 \\
 $$
+=== 3. Example: How can we describe the BNF formula using itself? ===
+\[
+\langle \text{BN formula} \rangle ::= \langle \text{rule} \rangle
+\]
+\[
+\langle \text{rule} \rangle ::= \langle \text{identifier} \rangle "::=" \langle \text{expression} \rangle
+\]
+\[
+\langle \text{identifier} \rangle ::= "\langle" \langle \text{letter} \rangle \mid \left\lbrace \langle \text{letter} \rangle \mid \langle \text{digit} \rangle \right\rbrace "\rangle"
+\]
+\[
+\langle \text{expression} \rangle ::= \langle \text{term} \rangle \left\lbrace "|" \langle \text{term} \rangle \right\rbrace
+\]
+\[
+\langle \text{term} \rangle ::= \langle \text{factor} \rangle \left\lbrace \langle \text{factor} \rangle \right\rbrace
+\]
+\[
+\langle \text{factor} \rangle ::= \langle \text{identifier} \rangle \mid \langle \text{terminal\_symbol} \rangle
+\]
+\[
+\langle \text{terminal\_symbol} \rangle ::= \left\lbrace \langle \text{character} \rangle \right\rbrace
+\]
+\[
+\langle \text{letter} \rangle ::= \langle \text{uppercase} \rangle \mid \langle \text{lowercase} \rangle
+\]
+\[
+\langle \text{uppercase} \rangle ::= A \mid B \mid C \dots Z
+\]
+\[
+\langle \text{lowercase} \rangle ::= a \mid b \mid c \dots z
+\]
+\[
+\langle \text{digit} \rangle ::= 0 \mid 1 \mid 2 \mid 3 \mid 4 \mid 5 \mid 6 \mid 7 \mid 8 \mid 9
+\]