diff --git a/lab-4/main_test.c b/lab-4/main_test.c
index d82f3eb..2a8af21 100644
--- a/lab-4/main_test.c
+++ b/lab-4/main_test.c
@@ -16,7 +16,7 @@ UTEST_MAIN();
 
 UTEST(parser, math) {
   // Must include the null character to terminate input
-  char string[] = "1+8/4-3;\0"; 
+  char string[] = "COMPUTE A = (b ** 2) - (4 * a * c)\0"; 
   YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));
 
   yylineno = 1;
@@ -28,20 +28,6 @@ UTEST(parser, math) {
   ASSERT_EQ(result, 0); 
 }
 
-UTEST(parser, missing_semi_colon) {
-  // Must include the null character to terminate input
-  char string[] = "1+8/4-3\0"; 
-  YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));
-
-  yylineno = 1;
-  int result = yyparse();
-
-  yy_delete_buffer(buffer);
-
-  // Assert the result to test correctness
-  ASSERT_EQ(result, 1); 
-}
-
 UTEST(parser, hello) {
   // Read sample file as input
   yyin = fopen("samples/hello-world.cbl", "r");
@@ -71,7 +57,7 @@ UTEST(parser, print) {
 
 UTEST(parser, branching) {
   // Must include the null character to terminate input
-  char string[] = "IF A > B THEN DISPLAY 'A is greater than B' ELSE DISPLAY 'B is greater than A'\0"; 
+  char string[] = "IF A > B DISPLAY 'A is greater than B' ELSE DISPLAY 'B is greater than A'\0"; 
   YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));
 
   yylineno = 1;
@@ -81,10 +67,23 @@ UTEST(parser, branching) {
 
   // Assert the result to test correctness
   ASSERT_EQ(result, 0); 
-} 
+}
 
 UTEST(parser, looping) {
-  char string[] = "PERFORM VARYING I FROM 1 BY 1 UNTIL I > 10 MOVE I TO A(I)\0"; 
+  char string[] = "PERFORM VARYING I FROM 1 BY 1 UNTIL I > 10\0"; 
+  YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));
+
+  yylineno = 1;
+  int result = yyparse();
+
+  yy_delete_buffer(buffer);
+
+  // Assert the result to test correctness
+  ASSERT_EQ(result, 0);
+}
+
+UTEST(parser, assignment) {
+  char string[] = "MOVE I TO A(I) MOVE 1 TO I COMPUTE discriminant = (b ** 2) - (4 * a * c)\0"; 
   YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));
 
   yylineno = 1;
@@ -121,17 +120,3 @@ UTEST(parser, quadratic) {
   // Assert the result to test correctness
   ASSERT_EQ(result, 0); 
 } 
-
-UTEST(parser, boolean) {
-  // Must include the null character to terminate input
-  char string[] = "IF A > B THEN Var = TRUE ELSE Var = FALSE\0"; 
-  YY_BUFFER_STATE buffer = yy_scan_buffer(string, sizeof(string));
-
-  yylineno = 1;
-  int result = yyparse();
-
-  yy_delete_buffer(buffer);
-
-  // Assert the result to test correctness
-  ASSERT_EQ(result, 0);
-}
diff --git a/lab-4/parser.bison b/lab-4/parser.bison
index 4e21a07..babfbd9 100644
--- a/lab-4/parser.bison
+++ b/lab-4/parser.bison
@@ -86,21 +86,16 @@ type            : TOKEN_KEYWORD_IDENTIFICATION
                 | TOKEN_KEYWORD_DATA
                 ;
 simple_stmt     : cbl_function
-                | cbl_function param 
+                | cbl_function op_parms 
                 | cbl_function assignment_stmt
-                | cbl_function param assignment_stmt
-                | cbl_function TOKEN_IDENT assignment_stmt
+                | cbl_function op_parms assignment_stmt
                 | if_branch 
+                | perform_stmt
                 ;
-expression      : op_parms
-                | bool
-                ;
-bool            : op_parms TOKEN_EQUAL op_parms
                 ;
 assignment_stmt : TOKEN_EQUAL ext_function
                 | TOKEN_EQUAL function
-                | TOKEN_KEYWORD_TO TOKEN_IDENT
-                | TOKEN_KEYWORD_TO TOKEN_IDENT categry_contain
+                | TOKEN_KEYWORD_TO op_parms
                 ;
 op_parms        : op_parms TOKEN_ADD op_parms
                 | op_parms TOKEN_SUB op_parms
@@ -109,14 +104,14 @@ op_parms        : op_parms TOKEN_ADD op_parms
                 | op_parms TOKEN_EXPONENTIAL op_parms
                 | op_parms TOKEN_LESS_THAN op_parms
                 | op_parms TOKEN_GREATER_THAN op_parms
+                | op_parms TOKEN_EQUAL op_parms
                 | TOKEN_SUB op_parms
                 | TOKEN_LEFT_PARENTHESIS op_parms TOKEN_RIGHT_PARENTHESIS
                 | TOKEN_IDENT
                 | TOKEN_INTEGER
-                ;
-param           : TOKEN_IDENT
                 | TOKEN_STRING
-                | param param
+                | TOKEN_SPACE
+                | op_parms op_parms
                 ;
 function        : op_parms
                 ;
@@ -127,11 +122,14 @@ cbl_function    : TOKEN_DISPLAY
                 | TOKEN_KEYWORD_COMPUTE
                 | TOKEN_PERFORM
                 ;
-if_branch       : TOKEN_IF expression
-                | TOKEN_ELSE_IF expression
+if_branch       : TOKEN_IF op_parms
+                | TOKEN_ELSE_IF op_parms
                 | TOKEN_ELSE statement
                 | TOKEN_END_IF
                 ;
+perform_stmt    : TOKEN_PERFORM TOKEN_VARYING TOKEN_IDENT TOKEN_KEYWORD_FROM TOKEN_INTEGER TOKEN_KEYWORD_BY TOKEN_INTEGER TOKEN_UNTIL op_parms
+                | TOKEN_END_PERFORM
+                ;
 data_space      : TOKEN_WORKING_STORAGE 
                 | TOKEN_KEYWORD_SECTION 
                 | TOKEN_DOT
@@ -142,6 +140,7 @@ data_category   : TOKEN_ALPHANUMERIC
                 | TOKEN_IMPLIED_DECIMAL
                 ;
 categry_contain : TOKEN_LEFT_PARENTHESIS TOKEN_INTEGER TOKEN_RIGHT_PARENTHESIS
+                | TOKEN_LEFT_PARENTHESIS TOKEN_IDENT TOKEN_RIGHT_PARENTHESIS
                 ;
 complete_category: complete_category complete_category  
                 | data_category categry_contain
diff --git a/lab-4/scanner.flex b/lab-4/scanner.flex
index 5c97694..4b7a148 100644
--- a/lab-4/scanner.flex
+++ b/lab-4/scanner.flex
@@ -6,7 +6,7 @@ DIGIT [0-9]+
 %%
 
 (" "|\t|\n) /* skip whitespace */
-\*>\ ?.* { return TOKEN_COMMENT; }
+\*>\ ?.*
 IDENTIFICATION { return TOKEN_KEYWORD_IDENTIFICATION; }
 DIVISION { return TOKEN_KEYWORD_DIVISION; }
 PROGRAM-ID { return TOKEN_PROGRAM_ID; }