diff --git a/labs/03/analyzer.l b/labs/03/analyzer.l
new file mode 100644
index 0000000..49a739f
--- /dev/null
+++ b/labs/03/analyzer.l
@@ -0,0 +1,44 @@
+/* 	
+	STUDENT INFORMATION
+	
+	Rodrigo López Guerra
+	A01737437
+
+	Laboratorio 3.
+
+	Lexical Analyzer Program
+*/
+
+/* 	DEFINICIONES     */ 
+
+%{
+#include "y.tab.h"
+%}
+
+/* 	OPCIONES     */ 
+
+%option noyywrap
+
+/* 	REGLAS Y TOKENS     */ 
+
+%%
+
+[aA] | 
+[tT]he	{ return ARTICLE; }
+
+[bB]oy | 
+[gG]irl	{ return NOUN; }
+
+[fF]lower	{ return GNOUN; }
+
+[tT]ouches |
+[lL]ikes | 
+[sS]ees	{ return VERB; }
+
+[wW]ith		{ return PREP; }
+
+\n          { return EOL; } 
+
+[ \t]+    { /* Ignora espacios en blanco */ }
+
+%%
\ No newline at end of file
diff --git a/labs/03/analyzer.y b/labs/03/analyzer.y
new file mode 100644
index 0000000..8bbf480
--- /dev/null
+++ b/labs/03/analyzer.y
@@ -0,0 +1,100 @@
+/* 	
+	STUDENT INFORMATION
+	
+	Rodrigo López Guerra
+	A01737437
+
+	Laboratorio 3.
+
+	YACC Syntax Interpreter
+*/
+
+/* 	DEFINICIONES     */ 
+
+%{
+#include <stdio.h>
+
+extern FILE *yyin;
+
+void yyerror(const char *s);
+int yylex(void);
+
+int set = 0;
+%}
+
+/* 	IDENTIFICADORES     */ 
+
+%token ARTICLE NOUN GNOUN VERB PREP EOL
+%start INPUT
+
+/* 	REGLAS     */ 
+
+%%
+
+/* Reglas de la Gramática Adaptada */
+
+INPUT: 					/* Espacio en blanco */ 
+	    					| EOL {/* Ignora espacios en blanco */ ;}
+            					| INPUT SENTENCE {set = 0;}
+	    					| INPUT error EOL { yyerrok; printf("FAIL\n"); set=0; }
+            					;
+
+SENTENCE:				NOUN_PHRASE VERB_PHRASE EOL { printf("PASS\n"); set=1; }
+            					;
+
+NOUN_PHRASE : 			CMPLX_NOUN
+            					| CMPLX_NOUN PREP_PHRASE
+            					;
+
+PREP_PHRASE: 			PREP CMPLX_NOUN 
+						| PREP CMPLX_GNOUN 
+            					;
+
+VERB_PHRASE : 			VERB
+	    					| VERB CMPLX_GNOUN
+            					| VERB NOUN_PHRASE
+            					;
+
+CMPLX_NOUN  : 			ARTICLE NOUN
+            					;
+
+CMPLX_GNOUN: 			ARTICLE GNOUN
+						;
+
+%%
+
+/* 	ERRORES GENERADOS     */ 
+
+void yyerror(const char *s) {
+}
+
+/* 	PROGRAMA PRINCIPAL     */ 
+
+int main(int argc, char **argv) {
+
+	FILE *fd;  // Declaración de la variable fd
+
+	if (argc == 2) {
+		fd = fopen(argv[1], "r");
+        	if (!fd){
+            		perror("Error: ");
+            		return (-1);
+        	}
+        	yyin = fd;  // Establecer yyin para leer del archivo
+    	}
+    	else {
+        	printf("Usage: ./analyzer FILENAME\n");
+        	return 1;  // Retornar con error si no se proporciona el nombre del archivo
+    	}
+
+	int result = yyparse();
+	if (set != 1){
+    		printf("FAIL\n"); // Se pone este comparador ya que al finalizar todas las reglas, YACC es incapaz de devolver la regla para un error.
+	}
+
+    	if (fd != NULL) {
+        	fclose(fd);  // Cerrar el archivo si está abierto
+    	}
+
+	return 0;
+}
diff --git a/labs/03/test.txt b/labs/03/test.txt
new file mode 100644
index 0000000..80f3545
--- /dev/null
+++ b/labs/03/test.txt
@@ -0,0 +1,5 @@
+
+a boy sees
+the boy sees a flower
+a girl with a flower likes the boy
+a flower sees a flower
\ No newline at end of file
diff --git a/labs/03/usage.txt b/labs/03/usage.txt
new file mode 100644
index 0000000..e8d318c
--- /dev/null
+++ b/labs/03/usage.txt
@@ -0,0 +1,15 @@
+1.- AT TERMINAL, SEARCH FOR THE LOCATION OF THIS FILES WITH THE "cd" COMMAND.
+
+2. RUN 
+	lex analyzer.l
+
+3. RUN 
+	yacc -d analyzer.y
+
+4. RUN 
+	gcc -o analyzer y.tab.c lex.yy.c -ll
+
+5. RUN
+	./analyzer test.txt
+
+NOTE: If you want to try the program with personalized sentences, you need to change the content of the file named "test.txt".
\ No newline at end of file