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SPEAKER 1: So let's take a
look at the puzzle logic gate.

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In this puzzle, you're presented
with a grid and a set of rules.

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And basically your
objective in this puzzle

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is to figure out which
student is of which year

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and which student is
seated at which terminal.

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And you can actually figure this
all this information out just

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from these four sentences
here, and then there's

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one more step that we'll get to
at the very end of the puzzle.

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But our goal is to figure
out who is what basically.

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So let's start looking
at the first clue.

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The student sitting at
terminal number eight

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has been in college longer than Charlie.

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What does this tell us?

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Well, it's actually tells
us a couple of things.

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First, we know that Charlie is
not seated at terminal eight,

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because they are two--

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we're talking about
two different people.

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So we can basically X that
one out or color it in red

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or whatever we want to do on our grid.

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The other thing we know is that the
student sitting at terminal eight

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cannot be a freshmen, because they've
been in college longer than Charlie.

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So we can also X that one out.

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And similarly, do we know that
Charlie cannot be a senior,

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because if they have been in
college longer than Charlie,

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Charlie can be the
oldest one of the group.

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So we can X all of those out.

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Now let's look at the second clue.

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This one's a little
more straightforward.

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It says Diane is a freshman.

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Well that actually gives
us a lot of information.

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We can actually color in
blue or green or check

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mark or whatever you want to
do to mark this on your grid

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that Diane is a freshmen.

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And it also tells us a little bit more.

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It also tells us that none of the
other three remaining students

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can possibly be freshmen, and it also
tells us that Diane can't possibly

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be a sophomore, junior, or senior.

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So we can actually out
all of those as well.

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The third clue is very similar.

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Charlie is sitting at terminal nine.

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So just like we did with
Diane being a freshman,

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we can similarly fill in
Charlie as at terminal nine

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and cross out all of the other
possibilities for terminal nine

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and for Charlie.

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And then we have our fourth clue here.

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Alice is one year behind the student
sitting at terminal number 10.

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So much like the first clue,
we actually get three pieces

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of information out of this directly.

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The first is that, of course,
Alice is not the student seated

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at terminal 10 for the same reason.

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We're talking about two
different people here.

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The next is that it also means that
the person who is seated at Terminal 10

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cannot be a freshmen because
Alice is one year behind them.

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And it also means that
Alice cannot be a senior,

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because she is one year behind
the students at terminal 10.

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But what does this also tell us?

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You'll notice that if I go back to
the previous slide for a second,

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there's only one possibility
left now for a senior

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if we look at that top left,
sort of, larger square,

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and that must mean that
Bob has to be a senior.

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We've excluded every other
possibility for who could be a senior,

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and Bob cannot be any other year.

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So now we have a couple
of conclusions that we

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can draw from what we have left.

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And let's start by looking at who
could be seated at terminal number 10.

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Let's take a look at
that fourth clue again.

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There are only two options left if
we look right here and right here.

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And the only two options
left are Bob and Diane.

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But now we have to, sort of,
synthesize the clues we've already had.

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It can't be Diane, because Diane
we know already is a freshmen

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and we know that Alice is
younger than the person who

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is seated at terminal number 10.

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So if Diane was seated there,
Alice couldn't be younger than her.

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And so Bob has to be the person who
is seated at terminal number 10.

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Now in addition, because
we know that Alice

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is one year younger than the person
seated at terminal number 10,

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that means that Alice has to be
a junior, because Bob is a senior

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and Bob is seated at terminal number 10.

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And that only leaves one
option left for Charlie

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there in that square on the top left,
which is that he must be a sophomore.

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And then finally, we
know that the student who

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is seated at terminal number eight has
been in college longer than Charlie

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and we know now that
Charlie is a sophomore.

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And among Diane and Alice
who are the last two left

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to figure out in that top right
square, that's only true of Alice.

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Alice is the only one who's been there
longer than Charlie of those two,

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so she has to be seen
at terminal number eight

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and Diane must be at terminal number 11.

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And now we, kind of, filled
out everybody's information,

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so we can also fill in everything in
that bottom grid as well based on all

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the information that we already have.

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Now for that last piece of the
puzzle here, originally, as you know,

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all of those squares that we just
filled in had letters in them.

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And if we just focus on
the ones now that reflect

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all of the true
relationships in this puzzle,

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we see these are the letters left.

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And if we read them from
left to right, top to bottom,

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we're left with the word architecture,
and that was the answer to this puzzle.