Problem identifying why a relation is not in 3NF
I am currently attempting to learn som rudimentary database stuff and I am stuck on this question; Given a relation R(A, B, C) with Fd´s: {A>C,B>C} why is R not in 3nf?
So the candidate key here is obviously AB, but I am not sure why this shouldnt be in 3NF since there is seemingly no transitive dependancies or partial dependencies since C depends upon both A and B (albeit seperately).
Am I completely off base here?
1 answer

There are different equivalent definitions of 3NF. One of them is that for each nontrivial functional dependency, either the determinant (left hand side attributes) is a superkey, or any attribute of the determinate (right hand side attributes) is prime (i.e. is part of any candidate key).
And since both A→C and B→C violates this definition, (A and B are not superkeys, and C is a not prime), the relation is not in 3NF.
The relation is neither in 2NF, since the dependency AB→C is a partial dependency: in fact we can remove either A or B and the dependency still holds.
See also questions close to this topic
 How to get all data from ef core many to many

Splitting multiple data in cell while copying rest of row
I am trying to normalize a Pokemon DB in to 1NF, however, I am unsure how to do this in Excel.
I am wanting to take the multiple data entries in 'Abilities' and split them and duplicate the row.
Original data
+++++  pokedex_number  name  classfication  abilities  +++++  1  Bulbasaur  Seed Pokemon  ['Overgrow', 'Chlorophyll']   2  Ivysaur  Seed Pokemon  ['Overgrow', 'Chlorophyll']   3  Venusaur  Seed Pokemon  ['Overgrow', 'Chlorophyll']  +++++
Desired data
+++++  pokedex_number  name  classfication  abilities  +++++  1  Bulbasaur  Seed Pokemon  Overgrow   1  Bulbasaur  Seed Pokemon  Chlorophyll   2  Ivysaur  Seed Pokemon  Overgrow   2  Ivysaur  Seed Pokemon  Chlorophyll   3  Venusaur  Seed Pokemon  Overgrow   3  Venusaur  Seed Pokemon  Chlorophyll  +++++

How should i guarantee consistency in database involving finance transaction operations
I am trying to figure out how to handle consistency in the database. In scenario:
User A has an accounting document in the database include a balance field representing the amount of his current money. (supposed initially he has 100$)
My system has many methods to charge his account.
 Suppose 2 methods occur at the same time, each method charges him for 10$, these steps occur concurrently in below orders:
 Method 1 READ his balance and store in memory (100$)
 Method 2 READ his balance and store in memory (100$) ... some business logics
 Method 1 UPDATE his balance by subtracting variable in memory by 10 (100$  10$) and then save it
 Method 2 UPDATE his balance by subtracting variable in memory by 10 (100$  10$) and then save it
This means he has been charged only 10$ instead of 20$.
I searched this situation a while and can not get it clear (sorry for my stupidity). Really appreciate yours helps to enlighten my featherbrained. :)

How to normalize open simplex noise values?
I want to make all the values generated by an open simplex 2D noise method fit in a range from zero to one, inclusive. I have tried the (value  min)/(max  min) equation I found here, but while the maximum value is correct, the minimum value found in my tests is 2.6123198888582956E9.
The OpenSimplexNoise class I use here can be found at it's page on GitHub.
How can I normalize the noise values here to the range [0, 1]?
public class NatureGenerator { private static final SplittableRandom Rand = new SplittableRandom(); public static double[][] generateNature() { double[][] worldMap = new double[900][1600]; // iterate through every pixel in world map for (int y = 0; y < worldMap.length; y++) { for (int x = 0; x < worldMap[0].length; x++) { // get noise value double noiseVal = noise.eval(x, y); // noise values without normalizing here are.. // maximum: 0.8643664287621713 // minimum: 0.8643664332781745 noiseVal = ((noiseVal + 0.8643664287621713) / (0.8643664287621713 + 0.8643664332781745)); // assign noise value to pixel worldMap[y][x] = noiseVal; } } // find minimum and maximum values in the 2D array worldMap double min = Double.MAX_VALUE; double max = Double.MIN_VALUE; for(double[] dd : worldMap) { for (double d : dd) { if (min > d) min = d; if (max < d) max = d; } } System.out.println("Maximum: " + max + " Minimum: " + min); return worldMap; } }

How to normalize the features extracted from Kinect C#?
I'm doing a project to extract the lip features with a Kinect in C#. My question is how to do a normalization with the features?
I think I have to do a function like this:
Nd = ( Cd * Fd ) / dFN
where Nd is the normalized distance, Cd is the current distance to the Kinect, Fd is the depth value of the forehead which every frame is normalized and dFN is the depth value for which every frame is normalized.
Also, a zscore normalization must be implemented:
z = (X  μ) / σ
where z is the result of the zscore normalization, X is the current feature value, μ is the mean obtained in one database and σ represents the variance.
How can I do this normalization based on the features?
Here is the function where I receive the features to normalize:
private void FaceReader_FrameArrived(object sender, HighDefinitionFaceFrameArrivedEventArgs e) { NewRecording(); using (var frame = e.FrameReference.AcquireFrame()) { if (frame != null) { frame.GetAndRefreshFaceAlignmentResult(_faceAlignment); UpdateFacePoints(); var vertices = _faceModel.CalculateVerticesForAlignment(_faceAlignment); var lipLeftCorner = vertices[(int)HighDetailFacePoints.MouthLeftcorner]; var lipRightCorner = vertices[(int)HighDetailFacePoints.MouthRightcorner]; var lipWidth = Math.Abs(lipRightCorner.X  lipLeftCorner.X); var lipTopCorner = vertices[(int)HighDetailFacePoints.MouthUpperlipMidtop]; var lipBottomCorner = vertices[(int)HighDetailFacePoints.MouthLowerlipMidbottom]; var lipHeight = Math.Abs(lipTopCorner.Y  lipBottomCorner.Y); var chinCenter = vertices[(int)HighDetailFacePoints.ChinCenter]; Console.WriteLine(lipLeftCorner.X.ToString()); Console.WriteLine(lipRightCorner.X.ToString()); Console.WriteLine(lipWidth.ToString()); Console.WriteLine(lipTopCorner.Y.ToString()); Console.WriteLine(lipBottomCorner.Y.ToString()); Console.WriteLine(lipHeight.ToString()); Console.WriteLine(lipTopCorner.Z.ToString()); Console.WriteLine(chinCenter.X.ToString()); Console.WriteLine(chinCenter.Y.ToString()); } } }

Device volume independent Android Visualizer Measurement
I want to normalize volume level of the
PCM
stream decoded by me that comes encoded over sockets by grouping short bursts ofsamples
. Instead of multiplying each sample with1(peakSample/32367.0)+1
, I useVisualizer
to get peak value and use it inLoudnessEnhancer
to add gain. (so, whenVisualizer
reports 3200 peak, I add 3200 astargetGain
withLoudnessEnhancer
)The problem isVisualizer
depends on the device volume even if I change the measurement scale ofVisualizer
. So, is there a way to get devicevolume independent measurement fromVisualizer
as I do not want to calculate rms and peak myself if there is already a well tested working android code. 
Show that 4NF when some FDs & MVDs hold implies BCNF when those FDs hold
How do I show that if relation schema R is in 4NF with respect to a set of FDs and MVDs then R is in BCNF with respect to the set of FDs implied by F?

Lossless decomposition of a relation
Let's say I have this relation R(P,Q,R,S) with FDs:
PQ → R
PQ → S
R → P
S → QHow do I find a lossless decomposition? I don't know if I should split it in 2 or 3 relations(R1,R2,R3..) and I can't find the answer.

How do deal with combined entity types when computing the closure of a set of attributes
I'm revising for coming exams, and I am having trouble understanding an example question regarding the closure of attributes. Here is the problem:
AB→C BE→I E→C CI→D Find the closure of the set of attributes BE, explaining each step.
I've found many explanations of the method of closure when the given step is a single entity type, say 'C', using Armstrong axioms, but I don't understand how to answer for 'BE'.

how can i solve this problem i cant make any normalization :(
here is logical design
A B C D E F.
and here are options.
A>C,F / C>D / B>E
problem is
"how can i make 2nf? 3nf? bcnf? "
i made prime key as A . here are my tried examples.
i tried what i can do for 2nf 3nf .this is my try of 2nf .
A C D F / A B E
and this is my try of 3nf .
A C F / C D and A B E
then how can i make boycecodd ???
.am i right about my 2nf and 3nf?  Confused on how to go from 2NF to 3NF

Is it possible that 3NF decomposition Algorithm will result in 3NF and BCNF Algorithm will result in BCNF? (same R)
is it possible that i will decompose some R with 3NF Algorithm and get a 3NF form
and if i will try to decompose the same R but this time with BCNF Algorithm is it possible that i will get BCNF form without sacrificing losslessness or dependency preservation?