diff --git a/ps-grammar/gprs/gprs.jsgf b/ps-grammar/gprs/gprs.jsgf
index ba22ccc6409740cf4db6041a87803318d6eab761..f7f86449b42a11825ddab8e02bcbe1d936966c65 100644
--- a/ps-grammar/gprs/gprs.jsgf
+++ b/ps-grammar/gprs/gprs.jsgf
@@ -2,9 +2,9 @@
 grammar ToBI_GPRS;
 public <task> = [<robot_name>] [(would | could) you] [please] <command> [please] [<robot_name>];
 
-<robot_name> = tobi | robot;
+<robot_name> = (tobi | robot);
 
-<command> = <bring_command> | <goto_command> | <find_command> | <follow_command> | <cleanup_command> | <show_command> | <pointat_command>;
+<command> = (<bring_command> | <goto_command> | <find_command> | <follow_command> | <cleanup_command> | <show_command> | <pointat_command>);
 
 <bring_command> = (<bringVerb> [<person>] [<article>] <grab_object> [<preposition> [<article>] <location>] [((to|into) [<article>] <second_location>)]) | (<bringVerb> [<article>] <person> <preposition> <article> <location>);
 <goto_command> = (<gotoVerb> <preposition> ([<article>] <location>));
@@ -15,39 +15,39 @@ public <task> = [<robot_name>] [(would | could) you] [please] <command> [please]
 <cleanup_command> = (<cleanupVerb> [<article> <room_class>]);
 <show_command> = (<showVerb> [<person>] (([<article>] <grab_object>)) | (([the (path|way) to] [<article>] <location>))); 
 
-<bringVerb> = bring | carry | retrieve | fetch | get | give | put | attend | deliver | convey | gather | (pick up) | take | lead | grasp;
-<findVerb> = detect | find | (search [for]) | (check [for]) | acquire | attain | obtain | (look for);
-<pointatVerb> = (point at) | denote | direct | indicate | suggest | show;
-<showVerb> = show | demonstrate | present | (point at) | denote | direct | indicate | suggest;
-<gotoVerb> = navigate | go | approach | move | run | travel | ride;
-<followVerb> = follow | chase | (come after);
-<learnVerb> = learn | remember | memorize | determine | gain | study | train;
-<cleanupVerb> = (clean up) | (tidy up) | clear | (do up) | (straighten up);
+<bringVerb> = (bring | carry | retrieve | fetch | get | give | put | attend | deliver | convey | gather | (pick up) | take | lead | grasp);
+<findVerb> = (detect | find | (search [for]) | (check [for]) | acquire | attain | obtain | (look for));
+<pointatVerb> = ((point at) | denote | direct | indicate | suggest | show);
+<showVerb> = (show | demonstrate | present | (point at) | denote | direct | indicate | suggest);
+<gotoVerb> = (navigate | go | approach | move | run | travel | ride);
+<followVerb> = (follow | chase | (come after));
+<learnVerb> = (learn | remember | memorize | determine | gain | study | train);
+<cleanupVerb> = ((clean up) | (tidy up) | clear | (do up) | (straighten up));
 
-<person> = someone | <personal_pronoun> | <person_name> | (person | man | woman | guy | girl | boy | human | robot);
-<personal_pronoun> = him | her | me;
-<person_name> = james|john|alfred|daniel|charles|luis|paul|richard|robert|steve|anna|beth|carmen|jennifer|jessica|kimberly|kristina|laura|mary|sarah;
+<person> = (someone | <personal_pronoun> | <person_name> | (person | man | woman | guy | girl | boy | human | robot));
+<personal_pronoun> = (him | her | me);
+<person_name> = (james|john|alfred|daniel|charles|luis|paul|richard|robert|steve|anna|beth|carmen|jennifer|jessica|kimberly|kristina|laura|mary|sarah);
 
-<grab_object> = <cleaning_class> | <drink_class> | <snack_class> | <food_class> | tool | (bathroom stuff) | cleaning_stuff | drinks | drink | snacks | snack | object | food | something | stuff | item | beverage;
-<cleaning_class> = brush | detergent | shampoo | sponge | toothpaste;
-<drink_class> = (orange juice) | beer | cola | (chocolate milk) | (energy drink) | (grape juice) | milk | water;
-<snack_class> = (chocolate cookies) | chips | biscuits | bread | pringles | (strawberry cookies);
-<food_class> = (baby food) | crackers | coffee | yeast | noodles | beans; 
+<grab_object> = (<cleaning_class> | <drink_class> | <snack_class> | <food_class> | (cleaning stuff)  | drink | snacks | snack | object | food | something | stuff | item | beverage);
+<cleaning_class> = (brush | detergent | shampoo | sponge | toothpaste);
+<drink_class> = ((orange juice) | beer | cola | (chocolate milk) | (energy drink) | (grape juice) | milk | water);
+<snack_class> = ((chocolate cookies) | chips | biscuits | bread | pringles | (strawberry cookies));
+<food_class> = ((baby food) | crackers | coffee | yeast | noodles | beans); 
 
-<location> = <appliance_class> | <shelf_class> | <seat_class> | <table_class> | <room_class> | <door_class> | <exit_class> | exit | door | seating | utensil | location | room | appliance | shelf | seat | table | somewhere | apartment | furniture;
+<location> = (<appliance_class> | <shelf_class> | <seat_class> | <table_class> | <room_class> | <door_class> | <exit_class> | exit | door | seating | utensil | location | room | appliance | shelf | seat | table | somewhere | apartment | furniture);
 
-<second_location> = <appliance_class> | <shelf_class> | <seat_class> | <table_class> | <room_class> | <door_class> | door | seating | utensil | location | room | appliance | shelf | seat | table | somewhere | apartment | furniture;
+<second_location> = (<appliance_class> | <shelf_class> | <seat_class> | <table_class> | <room_class> | <door_class> | door | seating | utensil | location | room | appliance | shelf | seat | table | somewhere | apartment | furniture);
 
-<appliance_class> = (waste bin) | fridge | stove;
-<shelf_class> = bar | sideboard | (right sidetable) | (left sidetable);
+<appliance_class> = ((waste bin) | fridge | stove);
+<shelf_class> = (bar | sideboard | (right sidetable) | (left sidetable));
 <seat_class> = <seating_class>;
-<seating_class> = sofa | armchair | bed;
-<table_class> = (kitchen table) | (hallway table) | (dinner table) | (couch table) ;
-<door_class> = (room door);
-<room_class> = kitchen | (living room) | bedroom | hallway;
-<exit_class> = (exit door) | (entry door);
+<seating_class> = (sofa | armchair | bed);
+<table_class> = ((kitchen table) | (hallway table) | (dinner table) | (couch table)) ;
+<door_class> = ((room door));
+<room_class> = (kitchen | (living room) | bedroom | hallway);
+<exit_class> = ((exit door) | (entry door));
 
-<preposition> = into | to | from | on;
-<further_preposition> = (on [top of]) | in | (next to) | at | near;
+<preposition> = (into | to | from | on);
+<further_preposition> = ((on [top of]) | in | (next to) | at | near);
 
-<article> = the | an | a | some | this;
+<article> = (the | an | a | some | this);