LMR

[JVMerlino]

Ditto here. Here are the moves/situations that I won't reduce:

-- First four moves in move ordering (includes the hash move)
-- remaining depth > 3
-- not a promotion, capturing or checking move
-- not a pawn move
-- not while in check
-- not in a mate threat situation as reported by the hash move

Very conservative. Don't like the depth > 3. Most of the advantage of LMR occurs when you reduce moves near the root, since this is an exponential gain based on depth. Ditto for pawn moves. Passed pawn moves, maybe. But there are a ton of totally hopeless pawn moves that can safely be reduced.

Perhaps John meant depth < 3?!

Indeed, yes, that was a typo. Sorry about that. I had read somewhere that dropping from LMR straight into qsearch should be avoided for stability reasons, and I saw it implemented this way somewhere. In other words, if your LMR has a max reduction of 3, then you shouldn't do it at depth 3 or less.

I had originally tried just ensuring that LMR wouldn't reduce depth to less than 1, but I think the point was some effect of what Bob was referring to -- that LMR is more effective near the root.

hmmmm.....

I am currently experimenting with much more aggressive reductions AND extensions, and getting pretty good results so far.

jm

[bob]

The point is that Windows ships in 32 bit mode by default and if you want the 64 bit Vista you need to spend a lot.

So, currenlty in 2009, the spread of 64 bit systems (cpu+os) is bottlenecked almost entirely just by marketing reasons of a single software company, no other reasons.

If Vista 64 would have been at the same price of the 32 bit counterpart now we would already running only 64 bit engines.

I really hate to defend Microsoft, but I think I have to.

Vista 64 was the same price as Vista 32.

OEM's chose to install Vista32 due to so many drivers and programs not working properly with Vista64.

If you think Vista32 compatability was bad, you should have tried Vista64 when it was released.

Although Microsoft required drivers to be available in both 32 & 64 bits, the 64 bit drivers were often not kept current (or at least not made as readily available as the 32 bit drivers.) For example, for my laptop, the Vista64 graphics & chipset driver is more than a year out of date over the Vista32 one, plus it's a more generic one. (For that, and other reasons, my laptop is running V32 and my desktop is V64.)

And as somebody who runs Vista64 on the desktop, I can tell you from experience that many programs today *still* don't work properly with a 64 bit Windows.

Oh sure, a lot of generic programs do. But anything that's 32 bit and that wants to hook into the OS or Explorer still often doesn't work right.


Although XP64 existed, its pentration was practically zero and driver support wasn't much better. Vista64 was Microsofts first real consumer 64 bit OS. They could have pushed harder and encouraged developers to make 64 bit clean programs, but they haven't. (Better 64 bit specific tools would have helped. As would a MingW GCC64 for hobbiests.)

Part of the problem was a lack of need for 64 bits in general and part of the problem was the expletive-deleted known as Vista. People who could stay with XP often chose to do so, even if it meant limiting them to 32 bits and less than 4g of memory.

Only the truely adventurous or 64 bit needy tried Vista64 when it was released. (Although in the past year or two, V64 has begun apearing much more often in retail systems.)

As a result, Win7/64 is going to be the real transitional OS to 64 bits. (Hopefully.)

And it's going to be up to the driver writers and the application programmers whether Win7 will be the last 32 bit Windows or not.

We had many of the same things happening when we went from 16 bit DOS (& Win 3) to Win9x.

The only real differences back then were: 1) going to 32 bits had more benefits, so more people were in a hurry to do so. 2) More tools more quickly. 3) Win9x was better than Vista.

Just bought my wife a new computer at home, came with vista-premium-64 installed. Not sure what you mean by "win9x was better than vista." Vista has run flawlessly on my wife's dual-core box. Windows 98/ME were both horrible failures. XP was somewhat better but far too susceptible to viruses and such.

[Carey]

The point is that Windows ships in 32 bit mode by default and if you want the 64 bit Vista you need to spend a lot.

So, currenlty in 2009, the spread of 64 bit systems (cpu+os) is bottlenecked almost entirely just by marketing reasons of a single software company, no other reasons.

If Vista 64 would have been at the same price of the 32 bit counterpart now we would already running only 64 bit engines.

I really hate to defend Microsoft, but I think I have to.

Vista 64 was the same price as Vista 32.

OEM's chose to install Vista32 due to so many drivers and programs not working properly with Vista64.

If you think Vista32 compatability was bad, you should have tried Vista64 when it was released.

Although Microsoft required drivers to be available in both 32 & 64 bits, the 64 bit drivers were often not kept current (or at least not made as readily available as the 32 bit drivers.) For example, for my laptop, the Vista64 graphics & chipset driver is more than a year out of date over the Vista32 one, plus it's a more generic one. (For that, and other reasons, my laptop is running V32 and my desktop is V64.)

And as somebody who runs Vista64 on the desktop, I can tell you from experience that many programs today *still* don't work properly with a 64 bit Windows.

Oh sure, a lot of generic programs do. But anything that's 32 bit and that wants to hook into the OS or Explorer still often doesn't work right.


Although XP64 existed, its pentration was practically zero and driver support wasn't much better. Vista64 was Microsofts first real consumer 64 bit OS. They could have pushed harder and encouraged developers to make 64 bit clean programs, but they haven't. (Better 64 bit specific tools would have helped. As would a MingW GCC64 for hobbiests.)

Part of the problem was a lack of need for 64 bits in general and part of the problem was the expletive-deleted known as Vista. People who could stay with XP often chose to do so, even if it meant limiting them to 32 bits and less than 4g of memory.

Only the truely adventurous or 64 bit needy tried Vista64 when it was released. (Although in the past year or two, V64 has begun apearing much more often in retail systems.)

As a result, Win7/64 is going to be the real transitional OS to 64 bits. (Hopefully.)

And it's going to be up to the driver writers and the application programmers whether Win7 will be the last 32 bit Windows or not.

We had many of the same things happening when we went from 16 bit DOS (& Win 3) to Win9x.

The only real differences back then were: 1) going to 32 bits had more benefits, so more people were in a hurry to do so. 2) More tools more quickly. 3) Win9x was better than Vista.

Just bought my wife a new computer at home, came with vista-premium-64 installed.

Even a lot of laptops are now starting to come with V64. It's taken this long the drivers & 64 bit compatability to improve enough for average person and for them to want 4g or more, etc.

Not sure what you mean by "win9x was better than vista." Vista has run flawlessly on my wife's dual-core box. Windows 98/ME were both horrible failures. XP was somewhat better but far too susceptible to viruses and such.

Vista of today is not the Vista that was released. This is especially true of the Vista64 situation.

Win95 & Win98 were much better matched to the hardware of the time than what Vista was when it was released. (And let's talk about Vista on a netbook... giggle....)

Also, there were something like 4 or 5 versions of Win95. The first release wasn't the best, but later versions improved much more quickly than what Vista did.

Win98 was actually pretty stable for most people. The biggest fault, in my opinion, was the install / uninstall situation, which often left a lot of junk installed. The same thing exists with Vista too. Right now I've probably got 7-10 programs installed that I can't actually uninstall. (This is on both Vista32 & Vista64.)

WinMe was a failure in almost everybody's eyes. That's why so many people call Vista WinMe Too.

And it's worthless to talk about viruses etc. That's simply inherent in computing with an OS on 90% of all computers. In straight comparison Win9x were more vulnerable than Vista, but comparing the threats available then to Win9x and to now for Vista, things were probably better back then. Simply fewer & less sophisticated threats to deal with back then.