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What does it mean to say that a set of functional dependencies is irreducible?
Wiki User
∙ 11y ago
Functional dependencies is group of people that try to make the world look nice by painting the eggs in everyday of their live, so a set of functional dependencies is irreducible means the colorful eggs
Wiki User
∙ 11y ago
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What does the word integerty mean?
it means that if you have a set of rules that you follow them and if somebody turns their back you still follow their rules instead of take advantage of the person that is there and also break the rules.
How do you say I miss you every hour every minute?
Say it like you mean it. Not like someone else told you to say it.
What does it mean had have and have had?
Well, they both mean the same thing but some people like to say 'had have' and some like to say 'have had'. It's just that they like to say it that way. Some people shorten the sentence to .........have..... and some like to say ..........had......... so there is no deference between them.
What does it mean when they say 0 in 3?
None out of 3.
What is volume in a restaurant?
You must say in what context you mean this.
What does it mean when a doctor say you have a significant functional overlay?
you getting over weight
Axioms for functional dependencies and inclusion dependencies?
4. Functional dependencyIn relational database theory, a functional dependency is a constraint between two sets of attributes in a relation from a database.Given a relation R, a set of attributes X in R is said to functionally determine another set of attributes Y, also in R, (written X → Y) if, and only if, each X value is associated with precisely one Y value; R is then said to satisfy the functional dependency X → Y. Equivalently, the projection is a function, i.e. Y is a function of X.[1][2] In simple words, if the values for the X attributes are known (say they are x), then the values for the Y attributes corresponding to x can be determined by looking them up in any tuple of Rcontaining x. Customarily X is called the determinant set and Y the dependent set. A functional dependency FD: X → Y is called trivial if Y is a subset of X.The determination of functional dependencies is an important part of designing databases in the relational model, and in database normalization and denormalization. A simple application of functional dependencies is Heath's theorem; it says that a relation R over an attribute set U and satisfying a functional dependency X → Y can be safely split in two relations having the lossless-join decomposition property, namely into where Z = U − XY are the rest of the attributes. (Unions of attribute sets are customarily denoted by mere juxtapositions in database theory.) An important notion in this context is a candidate key, defined as a minimal set of attributes that functionally determine all of the attributes in a relation. The functional dependencies, along with the attribute domains, are selected so as to generate constraints that would exclude as much data inappropriate to the user domain from the system as possible.A notion of logical implication is defined for functional dependencies in the following way: a set of functional dependencies logically implies another set of dependencies , if any relation R satisfying all dependencies from also satisfies all dependencies from ; this is usually written . The notion of logical implication for functional dependencies admits a sound and complete finite axiomatization, known as Armstrong's axioms.Properties and axiomatization of functional dependenciesGiven that X, Y, and Z are sets of attributes in a relation R, one can derive several properties of functional dependencies. Among the most important are the following, usually called Armstrong's axioms:[3]Reflexivity: If Y is a subset of X, then X → YAugmentation: If X → Y, then XZ → YZTransitivity: If X → Y and Y → Z, then X → Z"Reflexivity" can be weakened to just , i.e. it is an actual axiom, where the other two are proper inference rules, more precisely giving rise to the following rules of syntactic consequence:[4].These three rules are a sound and complete axiomatization of functional dependencies. This axiomatization is sometimes described as finite because the number of inference rules is finite,[5] with the caveat that the axiom and rules of inference are all schemata, meaning that the X, Y and Z range over all ground terms (attribute sets).[4]From these rules, we can derive these secondary rules:[3]Union: If X → Y and X → Z, then X → YZDecomposition: If X → YZ, then X → Y and X → ZPseudotransitivity: If X → Y and WY→ Z, then WX → ZThe union and decomposition rules can be combined in a logical equivalence stating that X → YZ, holds iff X → Y and X → Z. This is sometimes called the splitting/combining rule.[6]Another rule that is sometimes handy is:[7]Composition: If X → Y and Z → W, then XZ → YWEquivalent sets of functional dependencies are called covers of each other. Every set of functional dependencies has a canonical cover.
How do you say functional in a sentence?
The robot was fully functional.
How do you say functional in French?
Functional is 'fonctionnel' in French.
How do you read f2 in functional notation?
you say f of 2
What is dependency preservation?
Given a set of dependencies F on R, the projection of F on Ri, denoted by 'lTR(F) where Ri is a subset of R, is the set of dependencies X ---.. Y in P+ such that the attributes in X U Yare all contained in Ri• Hence, the projection of F on each relation schema Ri in the decomposition D is the set of functional dependencies in P+, the closure of F, such that all their left- and right-hand-side attributes are in Ri• We say that a decomposition D '= {R[, Rz, ... , Rm} of R is dependency-preserving with respect to F if the union of the projections of F on each Ri in D is equivalent to F; that is, (('lTR (F» U ... U ('lTR (F)W '= P+
What do you mean by functional dependancy in dbms?
Dependency means that the one entity dependents on another entity. This is also applicable for the Function also. For Example : If you trying to check the general function which tells you about the rooms availability, which consist of checkFreeRooms() and we can have the checkForACRooms() and CheckForSuits(), So the general function for checking Rooms dependents on the other rooms as above
What do structural-functional theorists say about achieving a balance of power between men and women?
Change is happening :)
What is the ending part of say what you mean and?
Say what you mean and mean what you say.
What does irreducible complexity mean?
Irreducible complexity is a concept meaning that an item has been reduced to the bare essentials required for it to work: if you take away any of the remaining pieces, what's left isn't just a less efficient mousetrap (or whatever), it's a pile of junk that does nothing. The term is usually used by creationists to argue that things like the bacterial flagellum motor can't have evolved, since you can take away proteins for a while and get a less and less efficient motor, but you eventually reach a point at which removing any more proteins doesn't give a motor at all. Opponents argue that the remaining pieces still could form something with a different function (say, an active transport channel) and say this proves nothing.
How many nations are there on earth?
The number of nations on earth could depend on what your position may be on questions such as Sri Lanka, Cyprus, Somalia and the status of portions of their territories and/or how you may rank autonomous territories or dependencies of a number of countries. One would generally, by UN standards, today say that there are 233 countries and country dependencies. According to the United Nations, there are 193 nations. However, this varies if you ask countries.
How many nationalities are on Earth?
The number of nations on earth could depend on what your position may be on questions such as Sri Lanka, Cyprus, Somalia and the status of portions of their territories and/or how you may rank autonomous territories or dependencies of a number of countries. One would generally, by UN standards, today say that there are 233 countries and country dependencies. According to the United Nations, there are 193 nations. However, this varies if you ask countries.
