diff -r 3a12e096f9a0 -r 3bf3f5bb067e videos/02-algo2.srt
--- a/videos/02-algo2.srt	Sun Oct 04 12:30:24 2020 +0100
+++ b/videos/02-algo2.srt	Sun Oct 04 22:20:25 2020 +0100
@@ -1,16 +1,16 @@
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 00:00:06,020 --> 00:00:09,945
-They come back after
+Welcome back. After
 this disappointment
 
 2
 00:00:09,945 --> 00:00:14,115
-and case of over promising
-and under achieving.
+and case of over-promising
+and under-achieving,
 
 3
 00:00:14,115 --> 00:00:17,295
-Let's have a look whether
+let's have a look whether
 we can recover from that.
 
 4
@@ -19,18 +19,18 @@
 
 5
 00:00:20,535 --> 00:00:23,790
-Then we looked at this end
-times vk expression and
+When we looked at this 
+n-times regular expression, we
 
 6
 00:00:23,790 --> 00:00:27,330
-be able to represent
+were not able to represent
 that directly.
 
 7
 00:00:27,330 --> 00:00:31,275
-We had two represented as a
-sequence record expression.
+We had to represent it as a
+sequence regular expression.
 
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 00:00:31,275 --> 00:00:32,850
@@ -38,12 +38,12 @@
 
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 00:00:32,850 --> 00:00:36,510
-So times one would be just a,
+So times-one would be just a,
 
 10
 00:00:36,510 --> 00:00:40,595
-t, times two would
-be a, and so on.
+times-two would
+be a o a, and so on.
 
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 00:00:40,595 --> 00:00:43,535
@@ -52,22 +52,22 @@
 
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 00:00:43,535 --> 00:00:47,960
-N equals 13, the record
+n equals 13, the regular
 expression becomes quite large.
 
 13
 00:00:47,960 --> 00:00:52,865
 And now the functions
-nullable and also derivative.
+nullable and also derivative,
 
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 00:00:52,865 --> 00:00:56,360
-They need to traverse
-this reg expression.
+they need to traverse
+this regular expression.
 
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 00:00:56,360 --> 00:00:59,060
-Remember this tree in sometimes
+Remember this tree, sometimes,
 
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@@ -82,39 +82,39 @@
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 00:01:04,535 --> 00:01:08,150
 And in particular, because
-our first reg expression was
+our first regular expression was
 
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 00:01:08,150 --> 00:01:11,840
-actually not just a bot
-a plus one. So b hat.
+actually not just a, but
+a + 1. So we had
 
 20
 00:01:11,840 --> 00:01:14,330
-In the case of 13,
-we had a plus one,
+in the case of 13,
+we had a + 1, a + 1,...
 
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 00:01:14,330 --> 00:01:17,330
-a plus one a plus born 13 times.
+a + 1... 13 times.
 
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 00:01:17,330 --> 00:01:20,150
-And this reg
-expression just grows,
+And this regular
+expression just grows
 
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 00:01:20,150 --> 00:01:25,475
-stay in number n. Just to
-show you this also encode,
+with the number n. Just to
+show you this also in code,
 
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 00:01:25,475 --> 00:01:28,115
-I'm Stern, This File rewarm
+I'm in the file re1.sc,
 
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 00:01:28,115 --> 00:01:30,920
-and D and I have a size function.
+and in the end I have a size function.
 
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 00:01:30,920 --> 00:01:33,140
@@ -123,22 +123,22 @@
 
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 00:01:33,140 --> 00:01:36,215
-argument and produces in teacher.
+argument and produces an integer.
 
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 00:01:36,215 --> 00:01:39,980
 And essentially it takes
-this rec expression scene as
+this regular expression, seen as
 
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 00:01:39,980 --> 00:01:44,045
-a tree and count how many
-nodes are in this tree.
+a tree and counts how many
+nodes there are in this tree.
 
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 00:01:44,045 --> 00:01:49,490
-And so if I take this even
-one reg expression, this one,
+And so if I take this EVIL1
+regular expression, this one,
 
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 00:01:49,490 --> 00:01:52,160
@@ -147,49 +147,49 @@
 32
 00:01:52,160 --> 00:01:54,680
 can already see
-for any cross one,
+for n = 1,
 
 33
 00:01:54,680 --> 00:01:56,540
 the size of this
-record expression is
+record expression is 5
 
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 00:01:56,540 --> 00:01:59,615
-five and you see it
+and you see it
 slowly increases.
 
 35
 00:01:59,615 --> 00:02:02,150
-And this 20 n equals 20.
+And this 20, i.e. n = 20,
 
 36
 00:02:02,150 --> 00:02:07,100
-The size of this record
-expression is SMOW already a 119.
+the size of this regular
+expression is now already 119.
 
 37
 00:02:07,100 --> 00:02:10,145
-So now the interesting
-line as this one.
+The interesting
+line is this one.
 
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 00:02:10,145 --> 00:02:13,295
-Remember it when we
+Remember, when we
 built the derivative,
 
 39
 00:02:13,295 --> 00:02:17,150
-very often parts of a reg
+very often parts of a regular
 expression gets copied.
 
 40
 00:02:17,150 --> 00:02:19,280
-So if you have like EVA,
+So if you have like EVIL1
 
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 00:02:19,280 --> 00:02:22,325
-one of 2019 nodes,
+of 20, and you have 119 nodes,
 
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 00:02:22,325 --> 00:02:25,475
@@ -198,15 +198,15 @@
 43
 00:02:25,475 --> 00:02:31,475
 And we want to see what's the
-resulting tree look like,
+resulting tree look like, i.e.
 
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 00:02:31,475 --> 00:02:32,780
-how many nodes it has.
+how many nodes does it have.
 
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 00:02:32,780 --> 00:02:34,985
-So I take here either one of 20
+So I take here EVIL1 of 20
 
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 00:02:34,985 --> 00:02:38,405
@@ -220,11 +220,11 @@
 
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 00:02:43,210 --> 00:02:45,680
-Okay, that takes away.
+Okay, that takes a while.
 
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 00:02:45,680 --> 00:02:48,410
-You see now this rec expression,
+You see now this recular expression,
 
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 00:02:48,410 --> 00:02:52,280
@@ -239,7 +239,7 @@
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 00:02:55,400 --> 00:02:58,430
 traverse these trees with
-a million plus nodes.
+8 million plus nodes.
 
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 00:02:58,430 --> 00:03:01,400
@@ -257,8 +257,8 @@
 
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 00:03:06,350 --> 00:03:09,050
-have an explicit and
-times reg expression.
+have an explicit 
+n-times regular expression.
 
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 00:03:09,050 --> 00:03:11,600
@@ -267,12 +267,12 @@
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 00:03:11,600 --> 00:03:13,415
 it to the sequence
-reg expression,
+regular expression,
 
 59
 00:03:13,415 --> 00:03:17,510
 let's just have a single
-wreck expression and times,
+regular expression n-times,
 
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 00:03:17,510 --> 00:03:20,540
@@ -280,16 +280,16 @@
 
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 00:03:20,540 --> 00:03:24,470
-a number and keeps that
-regular expression Small.
+a number, and keeps that
+regular expression small.
 
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 00:03:24,470 --> 00:03:27,095
-I'm here in the fire V2,
+I'm here in the file re2.sc,
 
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 00:03:27,095 --> 00:03:29,090
-which is also on Keats.
+which is also on KEATS.
 
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 00:03:29,090 --> 00:03:32,570
@@ -298,40 +298,40 @@
 
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 00:03:32,570 --> 00:03:33,860
-a wrecker expression for
+a regular expression for
 
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 00:03:33,860 --> 00:03:36,770
-N times the optional
-reg expression.
+n-times. The optional
+regular expression
 
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 00:03:36,770 --> 00:03:39,920
-Very leaf out at the
-moment because this a
+we leave out at the
+moment because this a?
 
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 00:03:39,920 --> 00:03:41,975
-optional is represented as
+is represented as
 
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 00:03:41,975 --> 00:03:44,645
-a plus one and doesn't
-explain too much.
+a + 1 and doesn't
+expand too much.
 
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 00:03:44,645 --> 00:03:47,375
-The really the culprit
-is this n times.
+The real culprit
+is this n-times.
 
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 00:03:47,375 --> 00:03:51,095
 And instead of expanding
-it n times, which has,
+it n-times, we just
 
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 00:03:51,095 --> 00:03:54,275
-take here a wreck expression
+take here a regular expression
 and a natural number,
 
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@@ -347,7 +347,7 @@
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 00:03:59,165 --> 00:04:01,370
 But by adding that
-reg expression,
+regular expression,
 
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 00:04:01,370 --> 00:04:05,150
@@ -356,11 +356,11 @@
 
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 00:04:05,150 --> 00:04:07,340
-derivative so that we have
+derivative. So that we have
 
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 00:04:07,340 --> 00:04:10,205
-to now calculate next
+to calculate next
 what they look like.
 
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@@ -380,38 +380,38 @@
 
 82
 00:04:19,580 --> 00:04:21,980
-R and B take in
-times of this are,
+r and we take it
+n-times of this r,
 
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 00:04:21,980 --> 00:04:25,220
-then indicates if n equals 0,
+then in case if n = 0,
 
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 00:04:25,220 --> 00:04:28,130
-we find that as the
-one reg expression.
+we definded that as the
+1 regular expression.
 
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 00:04:28,130 --> 00:04:30,380
-If n equals one,
+If n = 1,
 
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 00:04:30,380 --> 00:04:32,495
 it will be just a
-single copy of on.
+single copy of r.
 
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 00:04:32,495 --> 00:04:33,725
-If n equals two,
+If n = 2,
 
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 00:04:33,725 --> 00:04:35,270
-it will be two copies.
+it will be two copies in sequence.
 
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 00:04:35,270 --> 00:04:39,260
-Sequence if three, we have
+If three, we have
 three copies and so on.
 
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@@ -421,7 +421,7 @@
 
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 00:04:41,390 --> 00:04:44,285
-when these cases all nullable.
+when are these cases all nullable.
 
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 00:04:44,285 --> 00:04:47,810
@@ -429,11 +429,11 @@
 
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 00:04:47,810 --> 00:04:49,850
-then this will be defined as one,
+then this will be defined as 1.
 
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 00:04:49,850 --> 00:04:52,100
-so one can match
+So 1 can match
 the empty string.
 
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@@ -443,24 +443,24 @@
 
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 00:04:54,785 --> 00:04:57,725
-Okay, if any cross one,
+Okay, if n = 1,
 
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 00:04:57,725 --> 00:05:00,470
-when can this reg expression
+when can this regular expression
 match the empty string?
 
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 00:05:00,470 --> 00:05:02,000
-So vent should be nullable.
+So when should this be nullable?
 
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 00:05:02,000 --> 00:05:07,535
-Well, if nullable of our holes,
+Well, if nullable of r holds,
 
 100
 00:05:07,535 --> 00:05:09,860
-okay, so if I can match
+If it can match
 the empty string,
 
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@@ -475,11 +475,11 @@
 
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 00:05:14,870 --> 00:05:16,265
-So these are now two copies of
+So these are now two copies of r.
 
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 00:05:16,265 --> 00:05:20,690
-our well-posed copies need
+Well, both copies need
 to match the empty string.
 
 105
@@ -492,7 +492,7 @@
 
 107
 00:05:25,774 --> 00:05:28,520
-Ok? Similarly, in the third case,
+Similarly, in the third case,
 
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 00:05:28,520 --> 00:05:30,710
@@ -501,22 +501,22 @@
 109
 00:05:30,710 --> 00:05:33,230
 able to match the empty
-string. Men, is that the case?
+string. When is that the case?
 
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 00:05:33,230 --> 00:05:38,360
 Well, if nullable of
-our holes and so on.
+r holds and so on.
 
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 00:05:38,360 --> 00:05:48,754
 So we can actually define that
-if n equals 0, then true.
+if n = 0, then true,
 
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 00:05:48,754 --> 00:05:56,045
-Else we have to ask with
-nullable of our holes.
+else we have to ask whether
+nullable of r holds.
 
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 00:05:56,045 --> 00:05:58,550
@@ -525,7 +525,7 @@
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 00:05:58,550 --> 00:06:01,625
 have to implement for
-n times and nullable.
+n-times and nullable.
 
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 00:06:01,625 --> 00:06:04,280
@@ -533,16 +533,16 @@
 
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 00:06:04,280 --> 00:06:06,920
-the derivative of the n terms
+the derivative of the n-times
 
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 00:06:06,920 --> 00:06:10,175
-reg expression.
-It's not that easy.
+regular expression
+is not that easy.
 
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 00:06:10,175 --> 00:06:12,755
-So we have to look again
+We have to look again
 how it was defined
 
 119
@@ -552,12 +552,12 @@
 
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 00:06:16,010 --> 00:06:18,380
-The voice, our
+Otherwise, our
 algorithm will be again
 
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 00:06:18,380 --> 00:06:20,975
-quite slow if you don't
+quite slow if we don't
 spot that pattern.
 
 122
@@ -571,8 +571,8 @@
 
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 00:06:26,240 --> 00:06:29,885
-then r n times most
-defined as just one.
+then r n-times was
+defined as just 1.
 
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 00:06:29,885 --> 00:06:32,030