I agree there are no set definitions in chess. For example, the term "combination" seems to have different definitions depending on which book you read.

I hesitate to respond in case I am accused of arrogance or ignorance or something else...

I think that pseudo and sham sacrifice are the same thing. This is what I found on a trawl of the internet, from Wikipedia.

"In a true sacrifice, the sacrificing player will often have to play on with less material than his opponent for quite some time.

In a pseudo sacrifice, the player offering the sacrifice will soon regain the sacrificed material, or he may even gain more material than was originally sacrificed. A pseudo sacrifice of this latter type is sometimes known as a sham sacrifice, and will often lead to mate."

Before anyone else has a pop at me, that is just a quote from Wikipedia, with all the caveats that we need to attach to an internet resource that anyone can edit. But I would agree with it ... and I think it is consistent with Spielman's definition.

Here's the link to the article. Not sure I agree with all of it, so best if you make your own mind up. http://en.wikipedia.org/wiki/Sacrif...(chess)

One other definition I have found (from Golombek) introduces the idea of whether the advantage to be gained is calculable or incalculable. If the advantage is calculable, then it is a true or real sacrifice. If not, it is a "sacrifice for gain". I think this would accord with your idea of a move being a sacrifice for a lower graded player (because they could not calculate it to a forced advantage), whereas a GM or supercomputer might class the same move as a pseudo-sacrifice because they have calculated to a clear win.

BTW, that fount of all wisdom, Eric Schiller says this: "Tactics, sacrifices and combinations are three closely related chess concepts. There are no universally accepted boundaries between them and though each is "definitively" defined in various books and publications, the definitions vary widely."

Mind you, Schiller goes on to give the simplest definition of a sacrifice that I have seen yet: "A sacrifice is a simple concept. One side intentionally gives up material." He goes on to say that "Some sacrifices are calculated precisely while others are of a more speculative nature". This would seem to omit the definition of a sham sacrifice.

On balance, I prefer the real/ pseudo distinction from Spielman and Golombek to Schiller.

Instead he walks into unnecessary danger with 13.Kh1?, but even after that he probably could have survived.

Because I'm not Saemisch or Spielmann, much less Kasparov or Carlsen, I often make moves that offer material for what I hope will be ultimate advantage without having calculated the outcome in detail. I prefer to think of these as sacrifices, even if (by good luck) they turn out to be totally sound, as shown afterward by detailed analysis.

I think the main issue is one of "terminology theory". We define terms all the time. If we do a good job defining terms, those terms will make it possible to clearly express an idea in a natural way. A poor selection of terms will be awkward and confusing.

In this case, we are struggling with a poor choice of chess terms. We have "sham sacrifice" and "true sacrifice", which leaves the base term "sacrifice" dangling with no clear meaning. First, one should clearly define the base term, and then add qualifiers if necessary.

Also, I dislike the qualifier "true". If a sacrifice is not a "true sacrifice", what is it? Is it a wrong to call it a sacrifice at all?

Finally, I think that when the definition of a term depends on subjective ideas, it greatly reduces the communication value of the term. The definitions of "true sacrifice" and "sham sacrifice" are loaded with subjective ideas. Worse, the subjectiveness belongs to the players, not to us observers. So, we really have no right to be throwing these subjective terms around.

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All that to say this: I don't use the these terms because I don't want to propogate poorly defined terminology. I prefer to define "sacrifice" as any deliberate surrendering of material to achieve some purpose. It's simple and unambiguous.

I saw a similar argument a couple of years ago on an aviation website. One group quibbled with the english habit of referring to a concorde as just "Concorde" as if it were a proper name. This group argued that we don't talk about other aircraft in this way, so we shouldn't make any distinction for Concorde.

Ranged against this group were the Brits who argued that Concorde was called concorde, and that was that.

This argument got very heated and unpleasant, with people who had previously been good friends insulting each other (in similar terms to those that have been used agaist me recently). And no-one really understood why it had got so heated over such a small issue. Eventually the mods had to step in, close the thread and ban any further discussion on the subject.

What was really happening was a clash of cultures and different treatments of language. American English is generally rule-based, so the American posters could not understand how Concorde could be treated differently from other aircraft. By contrast, UK English is precedent-based, so under this way of thinking Concorde is called concorde because it just is.

Another example of this is that American pronunciation is generally phonetic, but UK pronunciation is based on custom and usage with many exceptions to the rules. So lieutenant is pronounced "leftenant" in the UK and "lootenant" in the US.

<Once> was being kind and gentle when he wrote < One school of thought is that language ought to be fixed by a standard definition; but another viewpoint is that language changes and evolves so standard definitions can only be a guide.>

Well, I agree with all of this, and also with what <Once> said about the nature and evolution of language.

I admit that my background is not in linguistics, but in mathematics and software development. I know that in these fields it behooves us to define terms that can be clearly understood, and that are distinct from other terms in ways (and only in ways) that are meaningful. If not, it makes communication error-prone and inefficient -- often resulting in arguments of semantics rather than the subject actually in question.

As you say, fuzziness and ambiguity are pervasive in natural language. Still, when we have an opportunity to define new terminology, it is to our advantage to give it some careful thought such that fuzziness and ambiguity are minimized, no?

<YouRang> Fine ideas, in principle. In practice, it's actually surprising how few deliberate constructions survive in the language. Most changes seem to come from slang, euphemism, and sound-changes which are themselves caused by everything from laziness to over-scrupulous care for correctness.

I find it's useful to pause occasionally and remember that every single word we use today was once a 'nasty' novelty -- slang, jargon, slipshod pronunciation, or whatever.

In this specific case, the word 'sacrifice' has connotations that vary between speakers. Any attempt to define it precisely will be influenced by these connotations, whether the definers know it or not.

For my own purposes, however, I shall still avoid terms like "true sacrifice" vs. "sham sacrifice", and my use of the word "sacrifice" (in chess) will be based on the precise and unambiguous definition I offered above.

< the precise and unambiguous definition I offered above.> And on *my* screen, 'above' is exactly where it is. But have you noticed how some people say 'above' (meaning 'below') and vice versa?

Anyway, I understand and agree with what you are saying about languages and how they are ambiguous and constantly evolving.

However, I still think there is such a thing as a poorly defined term and a well defined term. The difference between the two may be relative and temporary, but communication tends to flow better when using the terms that are well defined at the time.

One way to tell if a term is well defined or poorly defined is this: If it's well defined, then most people we easily agree to adopt that definition and use it. If it's poorly defined, then many people will resist using it and argue about what it really means -- such as what we have seen here.

This takes me back to my point: The way some people want to define 'sacrifice' (in chess) appears to be poorly defined simply because it prompts resistance and debate.

For me, the resistance is due because the word hardly has any meaning at all unless you precede it with the word 'true' or 'sham', and even then its use is questionable because these terms are subjective (i.e. my 'true' might be your 'sham', and nobody even knows for sure what it was to the player -- which is the case that really matters!)

But I do wonder if there's a cultural split happening here. UK English is such an evolved language that we have no problem accepting ambiguity, sloppy definitions, evolution, difference of opinion. UK English sometimes seems to have far more exceptions than rules.

By contrast, US English is far more orderly and rule-based, both for meanings and pronunciations.

So when people from opposite sides of the pond argue about definitions, the UK contingent tend more to ambiguity and evolution, and the US contingent insist on adherence to rules and definitions. It doesn't mean that either side is right or wrong. It's just a difference of approach.

I've developed this thought a little more on <domdaniel>'s forum, if you're interested.

So I actually have a lot of respect for people who say that the meaning of "sacrifice" is set because a particular authoritative book says so. Or advance a logical argument as you have done. In some cultures those would be compelling arguments.

But I can also respect the argument that the meaning of the word is ambiguous and evolves as usage changes.

I think that is partly the reason that this debate has become so heated - and probably will be heated whenever it comes up. The difference is not so much about the words themselves, it is about how different cultures handle ambiguity versus precision.