def add_fluents(self, turn):
        """ Called once per turn, this adds all 'fluents' for example,
            haveArrow[t+1] = haveArrow[t] OR shoot_act[t] """
        turn += 1

        breeze_perc.append(Bool("br_perc_%s" % (turn)))
        stench_perc.append(Bool("st_perc_%s" % (turn)))
        scream_perc.append(Bool("sc_perc_%s" % (turn)))
        glitter_perc.append(Bool("gl_perc_%s" % (turn)))
        bump_perc.append(Bool("bu_perc_%s" % (turn)))

        move_act.append(Bool("m_act_%s" % (turn)))
        right_act.append(Bool("r_act_%s" % (turn)))
        left_act.append(Bool("l_act_%s" % (turn)))
        shoot_act.append(Bool("s_act_%s" % (turn)))

        north.append(Bool("N_%s" % (turn)))
        east.append(Bool("E_%s" % (turn)))
        west.append(Bool("W_%s" % (turn)))
        south.append(Bool("S_%s" % (turn)))

        wumpus_alive.append(Bool("WumpusAlive_%s" % (turn)))
        have_arrow.append(Bool("HaveArrow_%s" % (turn)))

        tmp_loc = [[Bool("L_%s_%s_%s" % (turn, i + 1, j + 1)) for j in range(8)] for i in range(8)]
        tmp_ok = [[Bool("OK_%s_%s_%s" % (turn, i + 1, j + 1)) for j in range(8)] for i in range(8)]
        for thing in [tmp_loc, tmp_ok]:
            for row in thing:
                row.insert(0, row[1])
                row.append(row[-2])
            thing.insert(0, thing[1])
            thing.append(thing[-2])
        locations.append(tmp_loc)
        ok.append(tmp_ok)

        self.s.add(have_arrow[turn] == And(have_arrow[turn - 1], Not(shoot_act[turn - 1])))
        self.s.add(wumpus_alive[turn] == And(wumpus_alive[turn-1], Not(scream_perc[turn])))
        for x in range(1,9):
            for y in range(1,9):
                self.s.add(ok[turn][x][y] == And(Not(pits[x][y]), Not(And(wumpuses[x][y], wumpus_alive[turn]))))
                self.s.add(Implies(locations[turn][x][y], breeze_perc[turn] == breezes[x][y]))
                self.s.add(Implies(locations[turn][x][y], stench_perc[turn] == stenches[x][y]))
                # For current location:
                self.s.add(locations[turn][x][y] == Or(And(locations[turn-1][x][y], Or(Not(move_act[turn-1]),
                                                                                       bump_perc[turn])),
                                                       And(locations[turn-1][x-1][y], east[turn-1], move_act[turn-1],
                                                           Not(bump_perc[turn])),
                                                       And(locations[turn-1][x+1][y], west[turn-1], move_act[turn-1],
                                                           Not(bump_perc[turn])),
                                                       And(locations[turn-1][x][y-1], north[turn-1], move_act[turn-1],
                                                           Not(bump_perc[turn])),
                                                       And(locations[turn-1][x][y+1], south[turn-1], move_act[turn-1],
                                                           Not(bump_perc[turn]))))