1
00:00:03,110 --> 00:00:06,110
A random player is similar to legal
player.

2
00:00:06,110 --> 00:00:09,300
That it maintains a state and selects an
action for each state

3
00:00:09,300 --> 00:00:13,685
based solely on its legality in that state
without consideration of the consequences.

4
00:00:13,685 --> 00:00:16,550
A random player differs from a legal
player

5
00:00:16,550 --> 00:00:18,974
is not simply take the first legal move

6
00:00:18,974 --> 00:00:21,590
it finds but rather selects randomly from
among

7
00:00:21,590 --> 00:00:24,680
all of the legal actions available in that
state.

8
00:00:24,680 --> 00:00:26,720
Usually choosing a different move on
different occasions.

9
00:00:28,360 --> 00:00:31,060
The implementation of a random player's
almost

10
00:00:31,060 --> 00:00:32,850
identical to the implementation of a legal
player.

11
00:00:32,850 --> 00:00:34,700
In fact it's hard to see the difference
here.

12
00:00:34,700 --> 00:00:36,360
The only difference is in the play
handler.

13
00:00:37,420 --> 00:00:41,325
In the legal player the play handler
simply returns the first legal move.

14
00:00:41,325 --> 00:00:45,630
In a random player the play handler first
computes all legal moves

15
00:00:45,630 --> 00:00:49,820
using find legals and then selects one at
random from this list.

16
00:00:53,330 --> 00:00:55,730
Random players are no smarter than legal
players,

17
00:00:55,730 --> 00:00:58,870
however they often appear more interesting
because they're unpredictable.

18
00:01:00,310 --> 00:01:03,080
Also sometimes they avoid tracks, traps

19
00:01:03,080 --> 00:01:05,830
that befall consistent players like legal,
which

20
00:01:05,830 --> 00:01:08,520
sometimes can ma, maneuver themselves into
corners

21
00:01:08,520 --> 00:01:09,740
from which they are unable to escape.

22
00:01:11,300 --> 00:01:14,450
Random players are also used as standards
to show that

23
00:01:14,450 --> 00:01:17,460
general game players as specific methods
perform better than chance.

24
00:01:20,510 --> 00:01:24,270
now one downside on a random player is it
consumes slightly more compute time than

25
00:01:24,270 --> 00:01:26,030
a legal player, since it must compute

26
00:01:26,030 --> 00:01:29,080
all legal moves rather than computing just
one.

27
00:01:29,080 --> 00:01:31,280
Now, for most games, this is not a problem
but for games

28
00:01:31,280 --> 00:01:34,130
with a large number of possible actions
the difference can be noticeable.