@Override
	public void remove_child(Sentence_tree child){
		Sentence_tree[] new_children = new Sentence_tree[this.children.length - 1];
		int j = 0;
		for(int i = 0; i < this.children.length; i++){
			if(this.children[i] != child){ 
				new_children[j] = this.children[i];
				j++;
			}
		}
		this.children = new_children;
	}