183 lines
5.7 KiB
Markdown
183 lines
5.7 KiB
Markdown
# Assignment 1
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## Part A
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### Append
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```shell
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xsb
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```
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```prolog
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['A/append.P'].
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suffix([1,2], [1,2,3,4]).
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cut([1,2,3]).
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```
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### Reach
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generate input set
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```shell
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python randomgen.py [number of nodes]
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```
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```shell
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xsb
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```
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```prolog
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['A/reach.P'].
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timeReach.
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```
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| Input size | Way 1 | Way 2 | Way 3 | Way 4 |
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| ---------- | ----- | ----- | ------ | ------ |
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| 1000 | 0.0 | 0.0 | 0.765 | 0.766 |
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| 2000 | 0.0 | 0.0 | 3.047 | 3.047 |
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| 5000 | 0.0 | 0.0 | 18.828 | 18.953 |
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There is huge impact if we write edge(X,Y) before reach. But when I try this in swi-prolog(there is no cputime/1, so I cannot table it), there is no significant different between different ways of implementation.
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### Transitive closure and cycle
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```shell
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xsb
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```
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```prolog
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['A/cycle.P'].
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path(1,2) .
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cycle(1).
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```
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### N-queens
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```shell
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xsb
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```
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```prolog
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['A/queens.P'].
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timeNQueen(8).
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timeOneQueen(8).
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```
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| Number of queens | Time for 1 queen | Time for all queens |
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| ---------------- | ---------------- | ------------------- |
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| 8 | 0.0 | 0.047 |
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| 10 | 0.0 | 0.25 |
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| 12 | 0.0 | 7.796 |
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| 14 | 0.015 | 298.719 |
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| 16 | 0.094 | Too long to run |
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| 18 | 0.485 | Too long to run |
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| 20 | 2.796 | Too long to run |
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| 22 | 29.407 | Too long to run |
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I found somewhing interesting when I tried to use swi-prolog to program this question. The following code works in swi-prolog(not xsb):
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```prolog
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attacks((Row1, Col1), (Row2, Col2)) :-
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Row1 =:= Row2;
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Col1 =:= Col2;
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abs(Row1 - Row2) =:= abs(Col1 - Col2).
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no_attacks(_, []).
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no_attacks(Queen, [OtherQueen|OtherQueens]) :-
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\+ attacks(Queen, OtherQueen),
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no_attacks(Queen, OtherQueens).
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queen_positions(0, []).
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queen_positions(N, [(N, Col)|Queens]) :-
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N > 0,
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N1 is N - 1,
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queen_positions(N1, Queens),
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member(Col, [1,2,3,4,5,6,7,8]).
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legal_queens([]).
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legal_queens([Queen|Queens]) :-
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legal_queens(Queens),
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no_attacks(Queen, Queens).
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n_queens(N, Solution) :-
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queen_positions(N, Solution),
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legal_queens(Solution).
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```
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but it runs ridiculously slow(takes seconds to compute one solution of 8 queens).Then I tried to play with it and rearrange it a little bit and the answer I got (in A/queens.P) now runs much faster in swi-prolog and runs succesfully in XSB.
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## Part B
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### Reach
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generate input set
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```shell
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python randomgen.py [number of nodes]
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```
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```shell
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clingo --models 0 B/reach.lp
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```
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| Input size | Way 1 | Way 2 | Way 3 | Way 4 |
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| ---------- | ------- | ------ | ------ | ------ |
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| 10000 | 0.655s | 0.703s | 0.664s | 0.665s |
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| 20000 | 1.376s | 1.446s | 1.290s | 1.292s |
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| 50000 | 3.355s | 3.501s | 2.750s | 1.645s |
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| 100000 | 6.778s | 5.002s | 3.375s | 3.438s |
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| 200000 | 12.119s | 7.514s | 7.267s | 7.021s |
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Though it looks like the Way4 is way better tha Way 1(Almost twice as fast), but if we let the computer to rest for a while and rerun them the other way(start from 4, then 3, follow by 2 and 1), we got
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| Input size | Way 1 | Way 2 | Way 3 | Way 4 |
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| ---------- | ------ | ------ | ------ | ------- |
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| 200000 | 7.146s | 7.610s | 7.120s | 12.103s |
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It is exactly the other way around! I belive it is because the input file becomes too large
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(42 MByte), so it waste a lot of time to load it to memory then cache, and the following ones has much higher cache hits rate, so the first one takes way longer than the others.
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The runtime grows linearly respect to the input size, and there is no significant difference between different implementations.
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### N-queens
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```shell
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clingo --models 0 B/nqueens.lp
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```
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```shell
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clingo --models 1 B/nqueens.lp
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```
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| Number of queens | Time for 1 queen | Time for all queens |
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| ---------------- | ---------------- | ------------------- |
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| 8 | 0.004s | 0.006s |
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| 10 | 0.003s | 0.086s |
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| 12 | 0.004s | 4.909s |
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| 14 | 0.006s | Too long to run |
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| 20 | 0.011s | Too long to run |
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| 50 | 0.073s | Too long to run |
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| 100 | 0.463s | Too long to run |
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| 200 | 3.233s | Too long to run |
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| 500 | 35.073s | Too long to run |
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## Part C
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### N-queens
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| Number of queens | Max k |
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| ---------------- | ----- |
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| 4 | 3 |
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| 8 | 3 |
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| 10 | 4 |
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| 12 | 5 |
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| 14 | 5 |
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| 16 | 5 |
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| 18 | 5 |
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| 20 | 5 |
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## Extra Credit
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### I
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```shell
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python .\randompath.py 5000
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```
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```shell
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xsb
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```
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```prolog
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['A/cycle.P'].
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timePath.
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```
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| Number of Nodes | Way1 | Way 2 | Way3 |
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| --------------- | ------ | ------ | --------------- |
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| 200 | 0.0 | 0.0 | 0.407 |
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| 500 | 0.031 | 0.031 | 6.125 |
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| 1000 | 0.109 | 0.093 | 50.75 |
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| 2000 | 0.391 | 0.391 | Too long to run |
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| 5000 | 2.484 | 3.093 | Too long to run |
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| 10000 | 10.344 | 13.125 | Too long to run |
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### II
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See Extra/2.pl
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| Number of queens | Max k |
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| ---------------- | ----- |
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| 4 | 3 |
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| 8 | 3 |
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| 10 | 4 |
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| 12 | 5 |
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| 14 | 5 |
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| 16 | 5 |
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| 18 | 5 |
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| 20 | 5 | |