[QUOTE=Voyager]
I didn’t think about the lookahead problem. I assume translators of written works read it first to understand the context before translating, and translators of speech (like those in the UN) know the context. A machine translator of text would have to “understand” the book to do a good job, thus the need for an AI for a general solution.
I suck at human languages, except my own, but I did translate an SF magazine from Spanish to English for my own amusement, so I have some slight appreciation of how hard it is. I did not produce literature, even when compared to what I started with. 
[/QUOTE]
That is precisely why, as a tanslator and interpreter (the former is written, the latter is spoken) I seriously do not expect any software to give me a run for my money in my lifetime. Mind you, I am 58, so I can afford to say that. Given the amazing advances in cybernetics every single year, I might not say that if I were 20! 
You are right that context is everything. The aother problem computers have is that every word has a connotation and a denotation. The denotation is what it really means. The connotation is all the emotional and intangible baggage attached to it that make a word good or bad.
Take again one small example: Why did Lincoln say “Four-score and seven” instead of “eighty-seven” years"? Americans of the 1860s did not normally use such an archaic formulation in everyday life. Nobody came into a market and ordered “fourscore apples”.
Lincoln knew this of course. But he also knew that “fourscore” was an archaic formulation found in old English and, most importantly, in the King James Bible, with which most of his listeners were familiar. He knew that while the expression was not in common use, it would be just well-known enough not to leave his listeners going 
So why use this expression at all? Because the words immediately tell his listeners that he, the President, is about to say something important, something solemn and akin to a prayer. He is not just asking people to vote for a fellow Republican for Governor, for example.
Lincoln was about to state in a very short speech the essence of the democratic ideals he and the honoured dead was defending.
It was like a form of secular, national “Our Father” for a nation torn by war.
The use of an old English expression not only gave his listeners a slight feeling of hearing something sacred, but it also hearkened back to the English origins of American political institutions, to Magna Carta and even to the Declaration of Independence.
Now, my guess is that Lincoln probably opted for that expression after only a few seconds’ thought. And he probably did not consciously stop and dwell on all the connotations of those words as I have just done. More than likely, the expression popped into his brain, and was examined by BOTH his brain and his gut feelings, and he found it appropriate.
He might have agreed, after the fact, with the analysis I just offered of those words, but he would probably say that the words just seemed “right” to him.
Then again, there is another factor in literature. The overall rythm and sound of the words to create moods and effects.
In his “Elegy in a Country Churchyard” Grey says “The plowman homeward plods his weary way”. Wow! Can’t you just hear his tired steps in that line? Can’t you just FEEL the slow shuffle of a poor working man who is exhausted after a hard day? The effect is created with the use of long syllables like “plods” and letters like w in sequnce.
Imagine getting a computer to understand that? :dubious: Good luck!