The other day, I wrote a note for myself, and put it through the grammar checker at work.
I wanted to find out what was the earliest train on weekdays, and the earliest train on the weekend.
The note I wrote was ‘What is the earliest train weekdays and on the weekend?’
The grammar checker wanted to change it to ‘what are…’
What do you think?
I should mention that I almost never trust the spell checker or the grammar checker. I am just interested in what it does. It seems never right, in my opinion.
Maybe it thought ‘train’ modified ‘weekdays’ somehow?
It looks to me as though the grammar checker—which is, after all, pretty stupid—interpreted “earliest train” as words modifying “weekdays.” If that had been what you really meant, “what are” would indeed have been correct. (Sort of as in, “What are the earliest business weekdays when I can get an appointment?”)
You’ve asked about two trains - so they are.
But then you’d have to say ‘trains’ rather than ‘train’.
Which s/he should have done – there are, in fact, two trains in question.
Or at least more than one.
There could be up to seven, a different earliest train each day.
The problem with grammar checkers is that they only see your words and not your intent. We can easily understand your intent, and we can see that “is” should be “are” and “train” should be “trains”; both need to be changed, not one or the other. The software should have caught this and it was wrong not to.
But the programmers also have to try to compensate for the fact that people write their intent and not what the words would mean to an outsider reading them. That’s one of the biggest problems with all amateur writing, and lots of professionals make the same mistake fairly often. It’s a currently hopeless task.
And if we can’t get a simple grammar checker right, how can we possibly think we can make universal translators or other “coming soon” products?
[QUOTE=Exapno Mapcase]
There could be up to seven, a different earliest train each day.
QUOTE]
I know that the train system in question has the same timetable Monday-Friday and the same timetable Saturday and Sunday.I just do not know what the earliest train is.
That is part of the reason I wanted to know the earliest train on weekdays and the earliest train on the weekends.
Wait, let me try something:
“What is the earliest train tomorrow and the day after?”
“What are the earliest trains tomorrow and the day after?”
Neither one sounds wrong. But neither one is completely satisfactory. The problem with the former is that, as has been pointed out, you are asking about two trains (and besides, What is on second 
), but the latter is ambiguous: you could be asking for more than one train per day.
If you want to be crystal clear (come to think of it, are crystals necessarily all that clear?), you could go ahead and say, “What is the earliest train weekdays, and what is the earliest train on the weekend?” But since this is a note you wrote to yourself, as long as you know what you mean, word it whichever way you want to.
Stated that way, there is nothing left out – nothing understood. Stating it as you did originally, “What is the earliest train weekdays and on the weekend?”, there is something omitted. The full sentence as you might diagram it, would be “What is the earliest train [on] weekdays and [the earliest train] on the weekend?”
There is only one train that you wish to take, out of many possible ones.
Grammar checkers are often pretty stupid, and not as good as spelling checkers using today’s technology. They can be helpful, but don’t take them as gospel.