logic

问题 How would you transform the following prolog statement to predicate logic? hates(amy, X). 回答1: Using LaTeX's \forall to denote the universal quantifier, the meaning of hates(amy,x). is: \forall x hates(amy,x) In general, Prolog variables that occur in a program are universally quantified and Prolog variables that occur in a query are existentially quantified. For instance ?- hates(amy,x). would be represented by \exists x hates(amy,x) in FOL. 来源： https://stackoverflow.com/questions/25840140

问题 I'm trying to write a solver for End View Puzzles, using CLPFD (for those who are unfamiliar, here's a simple description http://www.funwithpuzzles.com/2009/12/abcd-end-view-a1.html ). I'm working on the constraint that I'll apply to each row/column, and running into some trouble. So I'm thinking it should look something like this: % NxN board, numbers from 0 to M in the row, Left/Right are the clues % corresponding to the row endviews(N,M,List,Left,Right):- length(List,M), domain(List,0,M),

问题 I am trying to design a query with OR and NAND operation, Can some one let me know Is the query is correct: Question 1: Is this query correct? select * from country where country_code='AL' UNION (SELECT * from country WHERE country_id NOT IN (SELECT country_id from country where country_name='Land islands' UNION SELECT country_id from country where country_code='AX' )); I created the query with the help of my another question of mine; Ref: Question 2: I want to use 5 query with AND,NOT,NAND

问题 Throughout my (short) career so far in programming (merely a student working on internship) I have noticed that when it comes to IF statements, there is two different ways of doing it. If we take foo as a boolean value: if(foo) { //do stuff } This is my preferred way of doing things when dealing with IF statements, if I'm looking for false I use: if(!foo) { //do more stuff } However, when some people see this they raise an eyebrow, suggesting that I may be stuck in a bad habit. But I wanted

问题 When I have a goal such as "∀x. P x" in Isabelle, I know that I can write show "∀x. P x" proof (rule allI) However, when the goal is "∀x>0. P x" , I cannot do that. Is there a similar rule/method that I can use after proof in order to simplify my goal? I would also be interested in one for the situation where you have a goal of the form "∃x>0. P x" . I'm looking for an Isar proof that uses the proof (rule something) style. 回答1: Universal quantifier To expand on Lars's answer: ∀x>0. P x is

问题 This question is in continuation with this one which I asked here: Now I have data something like this: Sno User Cookie 1 1 A 2 1 A 3 1 A 4 1 B 5 1 C 6 1 D 7 1 A 8 1 B 9 1 D 10 1 E 11 1 D 12 1 A 13 2 F 14 2 G 15 2 F 16 2 G 17 2 H 18 2 H So lets say we have 5 cookies for user 1 'A,B,C,D,E'. Now I want to count if any cookie has reoccurred after a new cookie was encountered. For example, in the above example, cookie A was encountered again at 7th place and then at 12th place also. NOTE We

问题 In MVC and MVP and similar patterns there's often the approach of the "passive view" which is as stupid (contains as few logic) as possible. This should facilitate unit testing and create a clearer separation of view and model. I know that those patterns come in very different flavours and especially the understanding of MVP seems to differ from article to article. Therefore my question is not "how do i implement this pattern correctly". I want to improve view and model separation and go for

问题 I have the following code (a primitive "RS-232 signalling" transmitter)... LIBRARY ieee; USE ieee.std_logic_1164.all; entity SerialTX is port( baud_clk : in std_logic; data : in std_logic_vector(7 downto 0); send : in std_logic; serial_out : out std_logic := '0'; busy : out std_logic := '0' ); end entity; ---------------------------------------- architecture behavioural of SerialTX is constant IDLE_BITS : std_logic_vector(10 downto 0) := "00000000001"; signal shifter : std_logic_vector(10

问题 I'm making MySql database, where I have film table: id title amount available description and copy table with foreign key film_id : id film_id And now I've written after delete trigger on copy : UPDATE `film` SET available = available - 1 WHERE OLD.film_id = id; And now I would like to write before delete trigger on film , due to fact that film is contrained by copy so I write: DELETE FROM copy WHERE copy.film_id = OLD.id; Here error occurs: Can't update table 'film' in stored function

问题 additive sequence. 3,3,6,9,15.... is called an additive sequence where the first two numbers must be the same..3+3=6,3+6=9 and so on. Also a number can be split into one of more digits to from the additive sequence. For eg: 12,122,436... In that sequence,12+12=24....12+24=36. The question is given the starting and ending numbers,find all the possible terms in the additive sequence. I get it that one sequence can be found pretty easily.But I have no clue how to take the bigger numbers like 122