DT connects determiners with nouns in certain idiomatic time
expressions like "next week" and "last Tuesday".

	      +-------MVp---------+
	      |               +DTi+
	      |               |   |
	I'm going to London next week		

Time Expressions
This might be a good place for a general discussion of time
expressions.

English contains many kinds of time expressions. The most common
uses of these expressions are analogous to prepositional phrases
(indeed, many time expressions are prepositional phrases). Time
expressions therefore often connect to the rest of the sentence 
with the same connectors as prepositional phrases: MVp+ (when
following a verb), Mp+ (when following a noun phrase), and CO+ (when
preceding a clause).

Many time expressions are single words or simple prepositional
phrases ("yesterday", "on Tuesday"), but many others are
idiomatic in construction, and use special-purpose link-types
like JT, DT, and Yt: "It happened three weeks ago / last
Tuesday morning / two days after the party". (Certain place
expressions like "five miles away", which use Yd, are similar
in this regard.) In such cases, decisions must be made,
sometimes rather arbitrarily, about which word in the time
expressions will serve as the head, i.e., will make the MV
connection to the rest of the sentence.

When time expressions contain a preposition or conjunction,
that word is almost always the head of the expression. Often
the head word is modified by a quantity expression, using a Yt
link (see "Y"). There are many time expressions, however,
which do not use prepositions or conjunctions, such as this
one:
	      	       
	I'm going to London next week

With a phrase like "next week", we make "week" the head of the
expression (we create a special "week.i" dictionary entry for
such nouns); we use DTi to attach a word like "next" (or "last"). We
then give "week.i" the usual prepositional phrase expressions: MVp-,
Mp-, CO+.

	week.i: DTi- & (MVp- or Mp- or CO+);
	next: DTi+;

	      +-------MVp---------+
	      |               +DTi+
	      |               |   |
	I'm going to London next week		

A phrase like "next week" can also be used a noun phrase. 

	1.I'll be free after next week
	2.Next week would be good
	3.Are you ready for next week

With certain prepositions, time expressions are very common as
objects: "after", "by", "until" (ex. 1). For these we use JT
(see "JT").  Other noun-phrase uses of time expressions are
less common, and rather colloquial (exx. 2-3). Therefore we
give "week.i" the usual "S+ or O- or J-" complex for nouns,
but we give it a cost of 2.

week.i DTi- & (MVp- or Mp- or CO+ or JT- or [[S+ or O- or J-]]);

With phrases like "this week" and "every week", we must do
something similar. However, there is an important difference
between "this week" and "next week". "This week" is a
well-formed noun phrase on its own, while "next week" is not. 
Therefore the noun-phrase uses of "this week" (like exx. 1-3
above) will take care of themselves, simply using the ordinary
noun entry "week.n". 

	  +-D-+--S-+
          |   |    |
	This week would be good

We need only worry about the prepositional phrase usages: "I
can see you this week". Therefore, for determiners like "this"
aand "every", as well as phrases like "the_next" and
"the_previous", we create a DTn connector, conjoined with the
prepositional-phrase connectors of "week.i" but not the
noun-phrase connectors:

	week.i: ((DTn- or DTi-) & (MVp- or Mp...)) or 
		(DTi- & (JT- or [[S+ or O-...]])

	this: DTn+;
	next: DTi+;

Phrases can also be formed with all these determiners (both
the DTn+ ones and the DTi+ ones) with month and
day-of-the-week names. Again, such expressions occur most
commonly as prepositional phrases or JT objects (exx. 4-6),
but can also occur as noun phrases (exx. 7-8).  Again, we give
the noun-phrase usages a cost of 2.

	4. We should meet this Tuesday
	5. You should do it before next January
	6. Last Monday, I saw Fred
	7. Next Tuesday would be good
	8. Are you ready for next Monday

A special case is phrases with the word "all": "all day",
"all year". These can only be used prepositionally: "We worked
all day", "*All day is too long". For these, we use DTa, which
is conjoined on words like "day" with prepositional-phrase
connectors but not noun-phrase connectors.

Unlike words like "week", day and month names can be used as noun
phrases with no determiner at all (exx. 9-10). Day names are often
objects of "on", and month names are often objects of "in".
These are so common that it seems sensible to give them a cost
of 0; therefore we create special "ON" and "IN" connectors
for them (ex. 11).

	9. Monday would be good
	10. Are you ready for April

	       +---MV---+-ON-+
	       |        |    |
	11. I saw Fred on Monday		

Month names can be used with dates and years. For this we use
TM and TY. For this purpose, special categories have been
created for numbers which are common as years and
days-of-the-month.

	    		    +-----TY----+     
	  	       +-ON-+--TM-+ +-Xd+-Xc-+
	 	       |    |     | |   |    |
	I.p saw.v him on January 21 , 1990 ///// 

TD is used to connect day-of-the-week names to word like "evening":
"I saw him Tuesday evening". TA is used to connect adjectives like
"late" to month names: "We did it in late December". There are some
other subtle distinctions regarding time expressions which we will
not go into here; the following sentences illustrate some of them.

	I saw him Monday
	*I saw him January
	I saw him January 21
	*January 21, I saw him
	We did it on Jan 21
	*We did it in Jan
	*I saw him on early January 21
	Monday's concert should be good
	This Monday's concert should be good
	This week's concert should be good
	The Monday concert should be good
	*The this week concert should be good
	I saw him in January 1990