query languages and the relational algebra

... program and its RA equivalent defines the two queries pUq and coalscp, the first on P and Q and the second on P only We will refer to them as the coalesce query and the until query, and observe that they ... count to The ITERATE statement updates the tuple in state by adding the new input value to the sum and to the count The TERMINATE statement returns the ratio between the sum and the count as the final ... the (state, symbol) pair, we obtain the next state, the new symbol and the motion direction for the tape head Then, the symbol pointed by the tape head is replaced by the new symbol We move the...

Ngày tải lên: 23/03/2014, 12:20

Ngày tải lên: 31/03/2014, 15:03

... abab}, and {aa, ab, aab, ba, bb, bab} The first of these is the union of {a} and {b}, the second is the concatenation of {a} and {b}, the third is the union of the first and second, the fourth is the ... sets {0, 1} and {1, 0} are the same, because both contain the elements and and no others; the set {0, 0, 1, 1, 1, 2} is the same as {0, 1, 2}, because they both contain 0, 1, and and no other elements ... example, then we must show that the truth values of the propositions on the left and right are the same, and there are eight cases, corresponding to the eight combinations of truth values for p, q, and...

Ngày tải lên: 31/05/2014, 00:58

... see, on the one hand, English learning and teaching has helped Vietnam in the new era of integration On the other hand, the learning and teaching of English at the expense of other languages is posing ... despite the need to learn and teach other languages other than English, as discussed in the previous part, the current situation does not encourage pupils and students to learn even “ major” languages ... done immediately is to raise the awareness of the whole society about the importance and the contribution of these languages On all the above facts, lessons, opinions and discussions so far, we...

Ngày tải lên: 06/11/2012, 15:36

... of body and mind by going to the boundless fairyland of your subject Think how the great mathematicians can weigh the earth and measure the stars, and reveal the laws of the universe; and tell ... Therefore not get too much immersed in the mere details of your own problems Learn the Ten Commandments and a few other old standard formularies by heart, and repeat them every now and then And ... If they could talk, they might argue and quarrel for years; and vote; and write in the newspapers; and waste their own time and other people’s money; each trying to prove he was right But there...

Ngày tải lên: 15/03/2014, 00:20

... in the ~ and ~ strings, then the vocabulary of recursive nonterminals would have to be increased in proportion (The second clause in the definition of profligacy makes it irrelevant whether there ... p l e or the binding theory TG's based on the "projection principle" and the '~inding theory" have yet to be formulated with sufficient explicitness for it to be determined whether they have ... willing to pay the price of inventing new nonterminals ad hoc to construct it The content of the claim lies in the fact that linguists demand independent motivation for the nonterminals they postulate,...

Ngày tải lên: 24/03/2014, 01:21

... Outline  Relational Model Concepts  Relational Model Constraints and Relational Database Schemas  Update Operations and Dealing with Constraint Violations Relational Model Concepts  The relational ... by the theory of relations  We review the essentials of the relational approach in this chapter Relational Model Concepts  The model was first proposed by Dr E.F Codd of IBM in 1970 in the ... Data is based on the concept of a Relation  A Relation is a mathematical concept based on the ideas of sets  The strength of the relational approach to data management comes from the formal foundation...

Ngày tải lên: 12/05/2014, 11:55

... here Relational Algebra  The basic set of operations for the relational model is known as the relational algebra These operations enable a user to specify basic retrieval requests  The result ... from the table and discards the other columns The PROJECT creates a vertical partitioning – one with the needed columns (attributes) containing results of the operation and other containing the ... express the queries in tuple calculus where the SELECT clause mentions the attributes being projected, the FROM clause mentions the relations needed in the query, and the WHERE clause mentions the...

Ngày tải lên: 12/05/2014, 11:55

... equivalent iff when feeding first u and then v to the DFA, u and v drive the DFA to the same state From the point of view of the observer u and v have the same effect (reaching the same state) Definition ... construct these sets, and we have no intention of doing so One can start from scratch, and define the natural numbers, and then the integers and the rationals etc This is a very interesting process, and ... for the reader is to prove theorem 1.3.10 Just as the cons operator is the foundation of Lisp like programming languages, the pair is the foundation of most mathematics, and for essentially the...

Ngày tải lên: 10/08/2014, 18:20

... Categories of© relational 1995, 2005 DML Introduction Relational algebra and relational calculus are formal languages associated with the relational model Informally, relational algebra is a (highlevel) ... Limited 1995, 2005 Relational Algebra Relational algebra operations work on one or more relations to define another relation without changing the original relations Both operands and results are ... 23 Theta join (θ-join) Can rewrite Theta join using basic Selection and Cartesian product operations R S = σ F(R Χ S) F Degree of a Theta join is sum of degrees of the operand relations R and...

Ngày tải lên: 21/10/2014, 23:08

Ngày tải lên: 13/11/2014, 09:21

... the L2 word, so the learners can base themselves on the connotation of their native word to guess the connotation of the target word The closer the translation into L1 is to the word in L2, the ... They were also encouraged not to talk to and consult their friends for the answer When the allowed time was over, their works were collected whether they had finished or not The papers were then ... takes sky and heaven as an example At first, these two words denoted both the physical firmament and the spiritual realm of God and the angels Then sky came to denote just the physical, and heaven...

Ngày tải lên: 28/02/2015, 11:54

... describes the methodology of the thesis Specifically, the data for this research was collected in the forms of survey questionnaires and The participants of the survey questionnaires were teachers and ... to the teachers so that more information on the reality and problems they face and solutions implemented can be collected Then, questionnaires are also given to the students to investigate their ... shown in the form of percentages Among 1,2,3,4 questions for the students, as to questions 5,6,7,8 for the teachers Therefore, the results for the questions are presented in the percentage of the...

Ngày tải lên: 04/06/2015, 13:55

... related to the research area The following chapter will display the detailed description of the methodology, the procedures and the results of the study in the light of the above discussed theories ... students and the researcher) The class observations may identify gaps between what the teachers said in the questionnaires and what they actually did in their classroom Design of the study The study ... prepares handouts on which there is a song lyric with some gaps The students listen to the song and fill in the missing words After all the missing words are filled and checked by the teacher, the...

Ngày tải lên: 15/07/2015, 13:00

... P H Chơn and L M Hà, On May spectral sequence and the algebraic transfer, Manuscripta Math 138 (2012) 141-160, MR2898751 [8] P H Chơn and L M Hà, On the May spectral sequence and the algebraic ... We prove the Part (ii) of the lemma The others can be proved by a similar computation From Propositions 4.1.2 and 4.1.3, we see that dim [Σ5 (u4 )] = 21 KAMEKO’S HOMOMORPHISM AND THE ALGEBRAIC ... 372-383, MR3276753 [9] L M Hà, Sub-Hopf algebras of the Steenrod algebra and the Singer transfer, “Proceedings of the International School and Conference in Algebraic Topology, Hà Nô.i 2004”, Geom...

Ngày tải lên: 12/10/2015, 10:39

... elements in the cohomology of the Steenrod algebra [29], the following theorem is our main result Theorem 5.2 The element n0 ∈ Ext5,36 (Z/2, Z/2) is in the image of the algebraic transfer A The fact ... factors through the coinvariant ring [PE A E Hs ]Σs The reader who is familiar with the algebraic transfer may wonder about the action of the ON MAY SPECTRAL SEQUENCE AND THE ALGEBRAIC TRANSFER ... is a quotient of the cobar complex, and the differentials comes from that of the cobar complex as well We shall use this method in the proof of the main theorem in Section The algebraic transfer...

Ngày tải lên: 26/10/2015, 14:03