diff --git a/parse.c b/parse.c
index 042bbba..4ba8a73 100644
--- a/parse.c
+++ b/parse.c
@@ -88,10 +88,10 @@ Node *mkString(char *s)
     return node;
 }
 
-Node *mkId(char *s){
+Node *mkId(Symbol *s){
   
     Node *node= new(Id);
-    node->Id.symbol=createSymbol(s);
+    node->Id.symbol=s;
     return node;
 }
 
@@ -229,82 +229,85 @@ else { \
 
 
 
-void move(SymbolTable *symbolTable, int a) {
-    symbolTable->length++;
-    symbolTable->elements= realloc(symbolTable->elements,sizeof(Node*) * symbolTable->length);
-    printf("begin\n");
-    for (int i= symbolTable->length-1; i >a; i--) {
-        symbolTable->elements[i] = symbolTable->elements[i-1];
-        printf("\n");
-        for(int i= 0; i<symbolTable->length; i++) {
-            printf("number : %i, name : %s, value : a\n",i, symbolTable->elements[i]->name);
+
+
+Symbol *intern(char *name){
+    int left=0,right=symbolTable.length-1;
+    
+    while(left<=right){
+        int middle=(left+right)/2;
+        int comp=strcmp(name,symbolTable.elements[middle]->name);
+        
+        if(comp<0){
+            right=middle-1;
+        }
+        else if(comp>0){
+            left=middle+1;
+        }
+        else{
+            return symbolTable.elements[middle];
         }
     }
-    printf("end\n");
-}
-
-void addSymbolSorted(SymbolTable *symbolTable, Symbol *symbol) {
-    int a=0;
-    int b= symbolTable->length-1;
-    int c;
-    //1 <b-a => no infinite loop with a and c = 0 et b =1
-    while (1 < b - a ) {
-        c= (a+b)/2;
-        if (strcmp(symbolTable->elements[c]->name, symbol->name) < 0) {
-            a= c;
-        } else {
-            b= c;
+    
+    symbolTable.elements= realloc(symbolTable.elements,sizeof(symbolTable.elements[0]) * (symbolTable.length+1));
+    memmove(symbolTable.elements+left+1,symbolTable.elements+left,(symbolTable.length-left)*sizeof(symbolTable.elements[0]));
+    symbolTable.length++;
+    return symbolTable.elements[left]=createSymbol(name);
+
+}
+
+int binary_search(SymbolTable *st, char *c){
+    int start=0,end=st->length-1;
+    int m=0;
+    while(end-start>1){
+       
+        m=(end+start)/2; //printf("char : %s\n %s",c,st->elements[m]->name);
+       // printf("start : %i End : %i\n Compare : %i\n",start,end,strcmp(c,st->elements[m]->name));/**/
+        if(strcmp(c,st->elements[m]->name)==0){
+            return m;
+        }
+        else if(strcmp(c,st->elements[m]->name)<0){
+            end=m-1;
         }
+        else{
+            start=m+1;
+        }
+        m=(end+start)/2;
     }
-    //b>-1 <=> symboleTable->length > 0
-    // this if is here to know if we put the symbol before or after a
-    if (b>-1 && strcmp(symbolTable->elements[a]->name, symbol->name) < 0) {
-        a++;
+   // printf("Start : %i, m : %i, end : %i char : %s size :%i\n",start,m,end,c,st->length);
+    if(strcmp(c,st->elements[m]->name)<0){
+        return start;
     }
-    //we move all the symbols after a
-    move(symbolTable, a);
-    //we put the symbol at the right place
-    symbolTable->elements[a]->name = symbol->name;
-}
-
-int findSymbol(SymbolTable *symbolTable, char *name) {
-    for (int i= 0; i < symbolTable->length;i++) {
-        if (strcmp(symbolTable->elements[i]->name, name) == 0) {
-            return 1;
-        }
+    else{
+        return end;
     }
-    Symbol *symbol = createSymbol(name);
-    addSymbolSorted(symbolTable, symbol);
-    return 0;
+    
 }
 
-Node *findSymbolSorted(SymbolTable *symbolTable, char *name) {
-    int a=0;
-    int b= symbolTable->length-1;
-    int c;
-    //1 <b-a => no infinite loop with a and c = 0 et b =1
-    while (1 < b - a ) {
-        c= (a+b)/2;
-        if (strcmp(symbolTable->elements[c]->name, name) < 0) {
-            a= c;
-        } else {
-            if (strcmp(symbolTable->elements[c]->name, name) > 0) {
-                b= c;
-            } else {
-                return symbolTable->elements[c]->rule;
-            }
-        }
-    }
-    //b>-1 <=> symboleTable->length > 0
-    // this if is here to know if we put the symbol before or after a
-    if (b>-1 && strcmp(symbolTable->elements[a]->name, name) < 0) {
-        a++;
+
+void addSymbol(SymbolTable *symbolTable, Symbol *symbol) {
+
+    if(symbolTable->length==0){
+        
+        symbolTable->length++;
+        symbolTable->elements= realloc(symbolTable->elements,sizeof(Symbol) * symbolTable->length);
+        symbolTable->elements[0]=symbol;//printf("indice de %s = %i\n",symbolTable->elements[0]->name,0);
+        return;
     }
-    //we move all the symbols after a
-    move(symbolTable, a);
-    //we put the symbol at the right place
-    symbolTable->elements[a]= createSymbol(name);
-    return 0;
+    else{
+      
+        
+        symbolTable->length++;
+        symbolTable->elements= realloc(symbolTable->elements,sizeof(Symbol*) * symbolTable->length);
+        int indice=binary_search(symbolTable, symbol->name);
+        
+        for(int k=symbolTable->length-1;k>indice;k--){
+            symbolTable->elements[k]=symbolTable->elements[k-1];
+        }
+        symbolTable->elements[indice]=symbol;//printf("indice de %s = %i\n",symbolTable->elements[indice]->name,indice);
+
+     }
+
 }
 
 void setRule(SymbolTable *symbolTable, char *name, Node *rule) {
@@ -618,7 +621,7 @@ YY_ACTION(void) yy_1_dot(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_dot\n"));
   {
-#line 352
+#line 355
   __=mkDot();
   }
 #undef yythunkpos
@@ -632,7 +635,7 @@ YY_ACTION(void) yy_1_class(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_class\n"));
   {
-#line 350
+#line 353
    __=mkClass(yytext) ;
   }
 #undef yythunkpos
@@ -646,7 +649,7 @@ YY_ACTION(void) yy_1_string(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_string\n"));
   {
-#line 348
+#line 351
    __ = mkString(yytext) ;
   }
 #undef yythunkpos
@@ -660,8 +663,8 @@ YY_ACTION(void) yy_1_id(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_id\n"));
   {
-#line 346
-   __ = mkId(yytext) ;
+#line 349
+   __ = mkId(intern(yytext)) ;
   }
 #undef yythunkpos
 #undef yypos
@@ -675,8 +678,8 @@ YY_ACTION(void) yy_1_rule(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_rule\n"));
   {
-#line 344
-   __ = mkId(yytext) ;
+#line 347
+   __ = mkId(intern(yytext)) ;
   }
 #undef yythunkpos
 #undef yypos
@@ -691,7 +694,7 @@ YY_ACTION(void) yy_4_postfix(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_4_postfix\n"));
   {
-#line 340
+#line 343
    __ = s;
   }
 #undef yythunkpos
@@ -707,7 +710,7 @@ YY_ACTION(void) yy_3_postfix(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_3_postfix\n"));
   {
-#line 339
+#line 342
    s = mkPlus(s) ;
   }
 #undef yythunkpos
@@ -723,7 +726,7 @@ YY_ACTION(void) yy_2_postfix(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_2_postfix\n"));
   {
-#line 338
+#line 341
    s = mkStar(s) ;
   }
 #undef yythunkpos
@@ -739,7 +742,7 @@ YY_ACTION(void) yy_1_postfix(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_postfix\n"));
   {
-#line 337
+#line 340
    s = mkQuery(s) ;
   }
 #undef yythunkpos
@@ -755,7 +758,7 @@ YY_ACTION(void) yy_2_prefix(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_2_prefix\n"));
   {
-#line 335
+#line 338
   __ = p;
   }
 #undef yythunkpos
@@ -771,7 +774,7 @@ YY_ACTION(void) yy_1_prefix(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_prefix\n"));
   {
-#line 334
+#line 337
   __ = mkExc(p);
   }
 #undef yythunkpos
@@ -788,7 +791,7 @@ YY_ACTION(void) yy_2_and(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_2_and\n"));
   {
-#line 332
+#line 335
    __ = p ;
   }
 #undef yythunkpos
@@ -806,7 +809,7 @@ YY_ACTION(void) yy_1_and(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_and\n"));
   {
-#line 331
+#line 334
    __ = mkAnd(p, a); ;
   }
 #undef yythunkpos
@@ -824,7 +827,7 @@ YY_ACTION(void) yy_2_or(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_2_or\n"));
   {
-#line 329
+#line 332
    __ = a ;
   }
 #undef yythunkpos
@@ -842,7 +845,7 @@ YY_ACTION(void) yy_1_or(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_or\n"));
   {
-#line 328
+#line 331
   __ = mkOr(o, a) ;
   }
 #undef yythunkpos
@@ -860,7 +863,7 @@ YY_ACTION(void) yy_1_declaration(yycontext *yy, char *yytext, int yyleng)
 #define yythunkpos yy->__thunkpos
   yyprintf((stderr, "do yy_1_declaration\n"));
   {
-#line 326
+#line 329
    setRule(&symbolTable,get(i, Id, symbol)->name, e) ;
   }
 #undef yythunkpos
@@ -1143,7 +1146,7 @@ YY_PARSE(yycontext *) YYRELEASE(yycontext *yyctx)
 }
 
 #endif
-#line 359 "parse.leg"
+#line 362 "parse.leg"
 
 
 
diff --git a/parse.leg b/parse.leg
index fb91ec1..64fd7ef 100644
--- a/parse.leg
+++ b/parse.leg
@@ -81,10 +81,10 @@ Node *mkString(char *s)
     return node;
 }
 
-Node *mkId(char *s){
+Node *mkId(Symbol *s){
   
     Node *node= new(Id);
-    node->Id.symbol=createSymbol(s);
+    node->Id.symbol=s;
     return node;
 }
 
@@ -222,82 +222,85 @@ else { \
 
 
 
-void move(SymbolTable *symbolTable, int a) {
-    symbolTable->length++;
-    symbolTable->elements= realloc(symbolTable->elements,sizeof(Node*) * symbolTable->length);
-    printf("begin\n");
-    for (int i= symbolTable->length-1; i >a; i--) {
-        symbolTable->elements[i] = symbolTable->elements[i-1];
-        printf("\n");
-        for(int i= 0; i<symbolTable->length; i++) {
-            printf("number : %i, name : %s, value : a\n",i, symbolTable->elements[i]->name);
+
+
+Symbol *intern(char *name){
+    int left=0,right=symbolTable.length-1;
+    
+    while(left<=right){
+        int middle=(left+right)/2;
+        int comp=strcmp(name,symbolTable.elements[middle]->name);
+        
+        if(comp<0){
+            right=middle-1;
+        }
+        else if(comp>0){
+            left=middle+1;
+        }
+        else{
+            return symbolTable.elements[middle];
         }
     }
-    printf("end\n");
+    
+    symbolTable.elements= realloc(symbolTable.elements,sizeof(symbolTable.elements[0]) * (symbolTable.length+1));
+    memmove(symbolTable.elements+left+1,symbolTable.elements+left,(symbolTable.length-left)*sizeof(symbolTable.elements[0]));
+    symbolTable.length++;
+    return symbolTable.elements[left]=createSymbol(name);
+
 }
 
-void addSymbolSorted(SymbolTable *symbolTable, Symbol *symbol) {
-    int a=0;
-    int b= symbolTable->length-1;
-    int c;
-    //1 <b-a => no infinite loop with a and c = 0 et b =1
-    while (1 < b - a ) {
-        c= (a+b)/2;
-        if (strcmp(symbolTable->elements[c]->name, symbol->name) < 0) {
-            a= c;
-        } else {
-            b= c;
+int binary_search(SymbolTable *st, char *c){
+    int start=0,end=st->length-1;
+    int m=0;
+    while(end-start>1){
+       
+        m=(end+start)/2; //printf("char : %s\n %s",c,st->elements[m]->name);
+       // printf("start : %i End : %i\n Compare : %i\n",start,end,strcmp(c,st->elements[m]->name));/**/
+        if(strcmp(c,st->elements[m]->name)==0){
+            return m;
+        }
+        else if(strcmp(c,st->elements[m]->name)<0){
+            end=m-1;
+        }
+        else{
+            start=m+1;
         }
+        m=(end+start)/2;
     }
-    //b>-1 <=> symboleTable->length > 0
-    // this if is here to know if we put the symbol before or after a
-    if (b>-1 && strcmp(symbolTable->elements[a]->name, symbol->name) < 0) {
-        a++;
+   // printf("Start : %i, m : %i, end : %i char : %s size :%i\n",start,m,end,c,st->length);
+    if(strcmp(c,st->elements[m]->name)<0){
+        return start;
     }
-    //we move all the symbols after a
-    move(symbolTable, a);
-    //we put the symbol at the right place
-    symbolTable->elements[a]->name = symbol->name;
-}
-
-int findSymbol(SymbolTable *symbolTable, char *name) {
-    for (int i= 0; i < symbolTable->length;i++) {
-        if (strcmp(symbolTable->elements[i]->name, name) == 0) {
-            return 1;
-        }
+    else{
+        return end;
     }
-    Symbol *symbol = createSymbol(name);
-    addSymbolSorted(symbolTable, symbol);
-    return 0;
+    
 }
 
-Node *findSymbolSorted(SymbolTable *symbolTable, char *name) {
-    int a=0;
-    int b= symbolTable->length-1;
-    int c;
-    //1 <b-a => no infinite loop with a and c = 0 et b =1
-    while (1 < b - a ) {
-        c= (a+b)/2;
-        if (strcmp(symbolTable->elements[c]->name, name) < 0) {
-            a= c;
-        } else {
-            if (strcmp(symbolTable->elements[c]->name, name) > 0) {
-                b= c;
-            } else {
-                return symbolTable->elements[c]->rule;
-            }
-        }
-    }
-    //b>-1 <=> symboleTable->length > 0
-    // this if is here to know if we put the symbol before or after a
-    if (b>-1 && strcmp(symbolTable->elements[a]->name, name) < 0) {
-        a++;
+
+void addSymbol(SymbolTable *symbolTable, Symbol *symbol) {
+
+    if(symbolTable->length==0){
+        
+        symbolTable->length++;
+        symbolTable->elements= realloc(symbolTable->elements,sizeof(Symbol) * symbolTable->length);
+        symbolTable->elements[0]=symbol;//printf("indice de %s = %i\n",symbolTable->elements[0]->name,0);
+        return;
     }
-    //we move all the symbols after a
-    move(symbolTable, a);
-    //we put the symbol at the right place
-    symbolTable->elements[a]= createSymbol(name);
-    return 0;
+    else{
+      
+        
+        symbolTable->length++;
+        symbolTable->elements= realloc(symbolTable->elements,sizeof(Symbol*) * symbolTable->length);
+        int indice=binary_search(symbolTable, symbol->name);
+        
+        for(int k=symbolTable->length-1;k>indice;k--){
+            symbolTable->elements[k]=symbolTable->elements[k-1];
+        }
+        symbolTable->elements[indice]=symbol;//printf("indice de %s = %i\n",symbolTable->elements[indice]->name,indice);
+
+     }
+
 }
 
 void setRule(SymbolTable *symbolTable, char *name, Node *rule) {
@@ -341,9 +344,9 @@ postfix	= s:atom ( "?" -	{ s = mkQuery(s) }
 
 atom    = string | class | dot | rule
 
-rule = i:id !'='        { $$ = mkId(yytext) }
+rule = i:id !'='        { $$ = mkId(intern(yytext)) }
 
-id = < [a-zA-z_][a-zA-z_0-9]* > - { $$ = mkId(yytext) }
+id = < [a-zA-z_][a-zA-z_0-9]* > - { $$ = mkId(intern(yytext)) }
 
 string	= '"' < [^"]* > '"'     { $$ = mkString(yytext) } -