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Commit 8acde4da authored by Martin Mareš's avatar Martin Mareš
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English: concrete -> specific

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...@@ -400,7 +400,7 @@ efficient in the worst case --- imagine that your program controls a~space rocke ...@@ -400,7 +400,7 @@ efficient in the worst case --- imagine that your program controls a~space rocke
We should also pay attention to the difference between amortized and average-case We should also pay attention to the difference between amortized and average-case
complexity. Averages can be computed over all possible inputs or over all possible complexity. Averages can be computed over all possible inputs or over all possible
random bits generated in an~randomized algorithm, but they do not promise anything random bits generated in an~randomized algorithm, but they do not promise anything
about a~concrete computation on a~concrete input. On the other hand, amortized complexity guarantees an~upper about a~specific computation on a~specific input. On the other hand, amortized complexity guarantees an~upper
bound on the total execution time, but it does not reveal anything about distribution bound on the total execution time, but it does not reveal anything about distribution
of this time betwen individual operations. of this time betwen individual operations.
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...@@ -98,7 +98,7 @@ to read $\lceil N/B\rceil \le N/B+1$ consecutive blocks to scan all items. All b ...@@ -98,7 +98,7 @@ to read $\lceil N/B\rceil \le N/B+1$ consecutive blocks to scan all items. All b
be stored at the same place in the internal memory. This is obviously optimal. be stored at the same place in the internal memory. This is obviously optimal.
A~cache-aware algorithm can use the same sequence of reads. Generally, we do not know A~cache-aware algorithm can use the same sequence of reads. Generally, we do not know
the sequence of reads used by the optimal caching strategy, but any concrete sequence the sequence of reads used by the optimal caching strategy, but any specific sequence
can serve as an upper bound. For example the sequence we used in the I/O model. can serve as an upper bound. For example the sequence we used in the I/O model.
A~cache-oblivious algorithm cannot guarantee that the array will be aligned on A~cache-oblivious algorithm cannot guarantee that the array will be aligned on
...@@ -280,7 +280,7 @@ to tiles from the previous algorithm. Specifically, we will find the smallest~$i ...@@ -280,7 +280,7 @@ to tiles from the previous algorithm. Specifically, we will find the smallest~$i
the sub-problem size $d = N/2^i$ is at most~$B$. Unless the whole input is small and $i=0$, the sub-problem size $d = N/2^i$ is at most~$B$. Unless the whole input is small and $i=0$,
this implies $2d = N/2^{i-1} > B$. Therefore $B/2 < d \le B$. this implies $2d = N/2^{i-1} > B$. Therefore $B/2 < d \le B$.
To establish an upper bound on the optimal number of block transfers, we show a~concrete To establish an upper bound on the optimal number of block transfers, we show a~specific
caching strategy. Above level~$i$, we cache nothing --- this is correct, since we touch no caching strategy. Above level~$i$, we cache nothing --- this is correct, since we touch no
items. (Well, we need a~little cache for auxiliary variables like the recursion stack, but items. (Well, we need a~little cache for auxiliary variables like the recursion stack, but
this is asymptotically insignificant.) When we enter a~node at level~$i$, we load the whole this is asymptotically insignificant.) When we enter a~node at level~$i$, we load the whole
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...@@ -35,7 +35,7 @@ In other words, if we pick a~hash function~$h$ uniformly at random from~$\cal H$ ...@@ -35,7 +35,7 @@ In other words, if we pick a~hash function~$h$ uniformly at random from~$\cal H$
the probability that $x$ and~$y$ collide is at most $c$-times more than for the probability that $x$ and~$y$ collide is at most $c$-times more than for
a~completely random function~$h$. a~completely random function~$h$.
Occasionally, we are not interested in the concrete value of~$c$, Occasionally, we are not interested in the specific value of~$c$,
so we simply say that the family is \em{universal.} so we simply say that the family is \em{universal.}
} }
...@@ -844,7 +844,7 @@ all~$x_i$'s, we can get a~false positive answer if $x$~falls to the same bucket ...@@ -844,7 +844,7 @@ all~$x_i$'s, we can get a~false positive answer if $x$~falls to the same bucket
as one of the $x_i$'s. as one of the $x_i$'s.
Let us calculate the probability of a~false positive answer. Let us calculate the probability of a~false positive answer.
For a~concrete~$i$, we have $\Pr_h[h(y) = h(x_i)] \le 1/m$ by 1-universality. For a~specific~$i$, we have $\Pr_h[h(y) = h(x_i)] \le 1/m$ by 1-universality.
By union bound, the probability that $h(y) = h(x_i)$ for least one~$i$ By union bound, the probability that $h(y) = h(x_i)$ for least one~$i$
is at most $n/m$. is at most $n/m$.
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