The new Fritz 9 engine
By Peter Schreiner
Our latest Fritz 9 program comes with a completely rewritten chess engine.
The author is Frans Morsch of the Netherlands, who has been improving his chess
algorithms ever since the first version of Fritz appeared fourteen years ago.
Already the previous iteration of Fritz was well respected for its balanced
style of play, in all phases of the game. It hardly showed any weaknesses and
was a very unpleasant opponent in over-the-board games. Last year in Bilbao,
running on a simple notebook, it scored 3.5/4 points against the world class
GMs Topalov, Ponomariov and Karjakin. Fritz 8 was also considered one of the
most reliable and precise analysis partners by most of the top players.

Beautiful 3D graphics of Fritz 9
The improvement of the Fritz 9 engine is for the most part the result of
implanting a huge amount of chess knowledge into the program. The new code
allows this to be done with great efficiency. The program is so designed that
additional knowledge will hardly slow it down at all – which ensures
that it will not sacrifice tactical strength for general chess principles.
The properties of a chess position are largely determined by the pawn structure,
and this is where Fritz 9 has received much more generalised chess knowledge
than its predecessor. Another touchy point is king safety. Unlike human beings
chess programs tend to be oblivious to dangers looming against the king until
these dangers are revealed in concrete variations which the program can calculate.
This weakness is not immediately obvious when you play computers against each
other, but when they encounter strong opponents it may spell their downfall.
Fritz 9 has also been greatly improved in this area and can detect long-term
threats against the king long before they appear in the search tree. This does
not just lead to better defensive play, it also causes the program to sense
potential dangers to the enemy king and lauch devastating attacks based on
these weaknesses. So it becomes more and more difficult to play “anti-computer
chess” against the program, while at the same time it has become an even
more dangerous opponent for human players.
Finally the search algorithms have been greatly improved, with the new data
structure allowing the engine to use its chess knowledge very deep in the tree.
That is probably the most significant improvement. Fritz can now find meaningfull
moves even in very balanced positions when there are no tactical motifs to
guide its choice.
There was always a danger that these improvements would lead to better strategic
play against human opponents, but it could fail when Fritz was up against other
computers. Fortnunately this was not the case: first tests are showing that
it is considerably stronger than its predecessor against other chess programs
as well.
Let us take a look at some concrete positions and see how Fritz 9 handles
them.
Timman,J - Kramnik,V [E15]
GMA Wijk aan Zee NED (10), 22.01.2004

Black to play.
The Fritz 9 engine quickly finds Kramnik’s move, 12… Nh5!,
which according to experts is the most accurate way to achieve equality. Fritz
8 switches to 12…Qc7 and stays with this positionally inferior move.
Sunye Neto,Jaime - Kasparov,Garry
WchT U26 Graz, 1981

Black to play.
Here Fritz 9 finds Kasparov’s brilliancy, 42...Bxe3!!,
instantaneously. More remarkable is that it gives the full line and displays
a very high evaluation in favour of Black.

Fritz 9 figuring out Kasparov’s move
The game continued 43.fxe3 [43.Ne2 Nh2+ 44.Ke1 Rxg2 45.Qxe3
Nf3+ 46.Kf1 Rg1+!! 47.Nxg1 Rd1+] 43...Rdxg2! 44.Qc3! [44.Qxb6
Rh2 45.Ne2 Rgg2+–] 44...Rh2 45.Ne2 Kh7! [45...Rgg2 46.Qc8+?=]
46.Qc8?! [46.Qb4! f5! 47.Qb5 (47.Qf8 Rh1+ 48.Kf2 Nd2!) 47...f4!
48.Qb4 Nd2+! 49.Qxd2 (49.Ke1 f3 50.Kxd2 Rxe2+ 51.Kc3 Rxe3+ 52.Kd4 f2) 49...Rh1+
50.Kf2 f3!+–] 46...Rh1+ 47.Kf2 Nd2! [47...Nd2! 48.Ng3
Rh2+ 49.Ke1 Nf3+ 50.Kf1 Rxb2] 0-1. Note that Fritz 9 has understood all of
the above analysis and evaluates it correctly in under ten seconds.
Hydra - Adams,Michael
Man-Machine London (3), 23.06.2005

White to play.
In the third game of the match Hydra vs the 32-processor hardware-enhanced
Hydra chess machine (which defeated Adams by a 5.5:0.5 score) Hydra played
the very deep move 26.Ra6!, which won it universal praise.
Fritz 9 finds this move in about 15 seconds on a Centrino notebook, giving
it a substantially positive value (+0.79), while its predecessor sticks to
the inferior 26.Qf3 with a slight negative score. Incidentally the game ended
after 26…Qb7 27.Rd6 Be7 28.Bxh6 1-0.
Ivanchuk,Vassily - Jussupow,Artur
Candidates qf3 g/60 Brussels (9), 1991

Black to move.
Fritz finds the black brilliancy almost instantaneously: 33…Nf2!!
On modest hardware the program needs just three seconds, with full understanding
of all the intricacies involved coming after eight seconds.

The process of discovery: Fritz 9 finds 33…Nf2!! in Ivanchuk-Jussupow
in three seconds and understands it in eight.
Fritz 8 required considerably longer to find the win. The game ended with
the moves 34.Bxf4 Qxf4 35.Ne6 Qh2 36.Rdb1 Nh3 37.Rb7+ Kg8 38.Rb8+ Qxb8
39.Bxh3 Qg3 0-1.
Benchmarks
The speed of hardware has great influence on the playing strength of the
program. “Engine” – “Chess Benchmark” will run
an internal test on your system and give you values for the speed relative
to a benchmark processor (P3, 1.0 GHz) and the average nodes-per-second count.
You can compare these values for different hardware configurations. Here are
some reasonable values we have registered for common systems:
Computer System |
Speed |
kN/s |
Pentium 4 2.6 GHz |
1.51 |
726 |
Centrino 1.6 GHz Notebook |
2.19 |
1050 |
Centrino 2.0 GHz Notebook |
2.76 |
1325 |
Athlon 64 3700/2200 MHz |
2.66 |
1232 |
Dual core Athlon 4400/2200 MHz (with Deep Fritz) |
Single core |
2.71 |
1300 |
Both cores |
5.41 |
2600 |
P4 2.8 GHz hyperthreading |
2.32 |
1115 |
Note that Pentium processors with “Hyperthreading” are simply
simulating two processors. This will cause the benchmark program to find two
processors, but the benchmark will not be as high as you would expect from
a dual system. A dual core processor, on the other hand, will (or should) actually
double the speed of the program, as is the case of the dual Athlon in the table
above. The values for this system were supplied by John Nunn.

Fritz Chess Benchmark, running on a 2.0 GHz Centrino notebook
The program that actually performs the benchmark terst is called Fritz Chess
Benchmark.exe and can be found in the Programs directory of your C drive (in
\ChessBase\ ChessProgram9). It is about 450 KB in size and runs independently
of Fritz. So you can copy it on a memory stick and take it with you when you
are shopping around for a new computer.
Running the benchmark takes just one minute, so it is possible to test a
number of candidate machines in a short period of time. You should do this
before you decide on one. It is quite surprising to see that sometimes computers
which have nominally identical hardware can display considerable variance in
the chess benchmark.
From ChessBase Magazine 108