Learn Hardcore Indonesian: Sesi perkenalan di perpustakaan sore ini singkat. - The introduction session in the library this afternoon is short.

If you just say perkenalan, it can mean “an introduction” in a more general sense (e.g., an introduction to a book, or the act of people introducing themselves).
Sesi perkenalan emphasizes that it’s a scheduled segment or session in a program or event, like “the introduction part” of a meeting or orientation.

Why is there no word like “is” in the sentence? Why not Sesi perkenalan ... adalah singkat?

In Indonesian, when the predicate is an adjective (like singkat, “short”), the copula (“is/are/am”) is usually omitted.

So:

Sesi perkenalan ... singkat. = “The introduction session is short.”

Using adalah is:

Mostly for linking noun = noun (e.g., Dia adalah guru = He is a teacher.)
Sometimes used in formal written language before a noun phrase.

Because singkat is an adjective, you normally don’t use adalah here.
Sesi perkenalan ... adalah singkat sounds awkward or overly bookish, and most native speakers wouldn’t say it.

What is the function of di in di perpustakaan, and can it be replaced by something else?

di is a preposition meaning “in/at/on” depending on context.
di perpustakaan = “at the library” / “in the library”.

You generally cannot replace di here with another preposition if you mean a place.
Some related prepositions:

di = in/at/on (location)
ke = to (direction, movement towards)
dari = from (origin)

So:

di perpustakaan = at/in the library
ke perpustakaan = to the library
dari perpustakaan = from the library

How does perpustakaan relate to buku? Is there a pattern?

Yes, perpustakaan is derived from pustaka, an older word meaning “book” or “manuscript”.

The structure:

pustaka = book, manuscript
per- + pustaka + -an → perpustakaan = “a place for books” → library

This per- ... -an pattern often means “a place related to X” or “an institution related to X”:

perusahaan (from usaha = effort/business) → company, enterprise
perkantoran (from kantor = office) → office area/office complex

So perpustakaan is literally a “book place,” i.e. a library.

What does sore ini mean exactly, and how is it different from hari ini or nanti sore?

sore = late afternoon / early evening (roughly 3–6 or 7 pm, depending on context)
ini = this

So sore ini = “this afternoon (later today)” in the late-afternoon sense.

Compare:

hari ini = today (the whole day)
nanti sore = this afternoon later (future reference, stressing later on today)
tadi sore = earlier this afternoon

In your sentence, sore ini locates the session in time: “this afternoon (today).”
If you said hari ini, it would be more general: “today,” not specifically in the afternoon.

Why is sore ini in the middle of the sentence, not at the end like in English?

Indonesian word order is fairly flexible for time and place expressions, as long as it’s clear and natural.

Common patterns:

[Subject] [Place] [Time] [Adjective]
Sesi perkenalan di perpustakaan sore ini singkat.
[Subject] [Time] [Place] [Adjective]
Sesi perkenalan sore ini di perpustakaan singkat.
[Time] [Subject] [Place] [Adjective]
Sore ini sesi perkenalan di perpustakaan singkat.

The version you have is very natural:
Sesi perkenalan [subject] di perpustakaan [place] sore ini [time] singkat [description].

So “time in the middle” is not wrong; it’s common and often sounds smooth.

Why is there no word for “the” in sesi perkenalan or perpustakaan?

Indonesian has no articles like “a/an/the”. Whether it’s “a” or “the” is understood from context, or added with extra words if needed.

sesi perkenalan:
- can mean “an introduction session” or “the introduction session”
di perpustakaan:
- can mean “in a library” or “in the library”

If you really need to stress “this” or “that”, you can add:

ini = this
itu = that

For example:

sesi perkenalan ini = this introduction session
di perpustakaan itu = in that library / in the library (previously mentioned)

What does perkenalan come from? Is there a related verb?

Yes. Perkenalan is a noun derived from the verb kenal.

kenal = to know someone / to be acquainted with
berkenalan = to get to know each other, to make an acquaintance
perkenalan = introduction (the act or event of getting to know)

Rough breakdown:

kenal (root)
ber-kenal-an → berkenalan (verb: to get acquainted)
per-kenal-an → perkenalan (noun: an introduction / introductory session)

So sesi perkenalan is literally a “session of introduction / getting acquainted.”

What is the role of singkat in this sentence, and where does it normally go?

singkat is an adjective meaning “short” (in duration or in wording, not height).

In this sentence:

Sesi perkenalan di perpustakaan sore ini = the subject
singkat = the predicate (describing the subject)

Word order for adjectives describing a noun directly:

sesi singkat = short session

But here, singkat doesn’t modify the noun directly; it acts as the main statement:

Sesi … sore ini singkat. = “The session … is short.”

So:

Before noun: sesi singkat (a short session)
At the end of the full clause: … sore ini singkat. (is short)

What’s the difference between singkat and pendek? Could I say Sesi perkenalan ... pendek?

Both relate to “short,” but they are used differently:

singkat
- short in duration, length of time, or amount of content / wording
- Ex: Pidatonya singkat. = His speech was short.
- Sesi perkenalan ... singkat. = The session is short. ✔ (natural)
pendek
- short in physical length or height
- Ex: Rambutnya pendek. = Her hair is short.
  Dia pendek. = He/She is short (in height).

Using pendek for a session or meeting is not idiomatic.
So Sesi perkenalan ... pendek sounds wrong. Singkat is the correct choice here.

Is sesi perkenalan di perpustakaan sore ini singkat formal, informal, or neutral?

This sentence is neutral, slightly leaning toward formal / standard because of:

The loanword sesi, which is often used in meetings, trainings, and official programs.
Clear, standard grammar and no slang.

In casual speech you might hear something like:

Sesi kenalan di perpustakaan sore ini sebentar aja.
(The intro session at the library this afternoon is just brief.)

But as written, your sentence fits well in announcements, written notices, or polite conversation.

Could I move singkat earlier in the sentence, like Sesi perkenalan singkat di perpustakaan sore ini? Does that change the meaning?

Yes, but the nuance changes.

Sesi perkenalan di perpustakaan sore ini singkat.
- Statement about the specific session this afternoon:
  “The introduction session at the library this afternoon is short.”
- singkat is the main information (predicate).
Sesi perkenalan singkat di perpustakaan sore ini...
- Here singkat directly modifies sesi perkenalan → “a short introduction session”.
- This sounds like the beginning of a longer sentence, e.g.:
  Sesi perkenalan singkat di perpustakaan sore ini akan dimulai jam empat.
  “The short introduction session at the library this afternoon will start at four.”

So your original sentence is a complete statement.
With singkat immediately after sesi perkenalan, it becomes more like a noun phrase that usually needs more after it.

How would I make it plural, like “The introduction sessions at the library this afternoon are short”?

Indonesian usually doesn’t mark plural with -s like English. Plurality is often:

Understood from context, or
Marked by reduplication or quantifiers.

Options:

Use context only (most natural if already clear):
- Sesi perkenalan di perpustakaan sore ini singkat.
  Could mean “The introduction sessions … are short” if the context already mentions multiple sessions.
Pluralize “sesi” by reduplication:
- Sesi-sesi perkenalan di perpustakaan sore ini singkat.
  Literally “the introduction sessions … are short.”
Add a number or word like “some / several”:
- Beberapa sesi perkenalan di perpustakaan sore ini singkat.
  Some / several introduction sessions at the library this afternoon are short.

All are grammatical; which you choose depends on how explicit you want to be about plurality.