question stringlengths 9 1.07k | choices sequencelengths 2 6 | answer stringclasses 2
values |
|---|---|---|
You are working on a dataset with lots of outliers, and want to perform a regression task. Everything else being equal, and assuming that you do not do any pre-processing, which loss function will be less affected by these outliers? | [
"$\\mathcal{L}(y, \\hat{y})= (y - \\hat{y})^2$ (MSE)",
"$\\mathcal{L}(y, \\hat{y})= |y - \\hat{y}|$ (MAE)"
] | A |
How many integers $n$ between $1$ and $2021$ satisfy $10^n \equiv 1 \mod 11$? Check the correct answer. | [
"1010",
"183",
"505",
"990"
] | A |
Tick the \textbf{true} assertion. Let $X$ be a random variable defined by the visible face showing up when throwing a dice. Its expected value $E(X)$ is: | [
"3.5",
"3",
"1",
"4"
] | A |
Which of the following statements about coverage-guided fuzzing is/are correct? | [
"Redundant seeds in the corpus will reduce fuzzing efficiency.",
"Counting the number of times the covered code has been executed\n provides a more fine-grained view of program behavior than only\n \"covered/not covered\" binary code coverage.",
"Due to the coverage feedback, a small rando... | B |
Which of the following statements are true about DEP? | [
"DEP prohibits code injection but not code reuse.",
"A single bit is used to indicate that a memory region is DEP protected.",
"Even if it is called Enhanced Virus Protection on AMD hardware, it does not protect against viruses.",
"Data Execution Prevention is usually handled at byte-level granularity.",
"A... | B |
Which of the following statements is correct concerning the use of Pearson’s Correlation for user- based collaborative filtering? | [
"It measures whether different users have similar preferences for the same items",
"It measures how much a user’s ratings deviate from the average ratings I",
"t measures how well the recommendations match the user’s preferences",
"It measures whether a user has similar preferences for different items"
] | A |
When using linear regression, which techniques improve your result? (One or multiple answers) | [
"linear regression does not allow polynomial features",
"polynomial combination of features",
"adding new features that are non-linear combination of existing features",
"because the linear nature needs to be preserved, non-linear combination of features are not allowed"
] | B |
Let $C$ be a perfect cipher with $\ell$-bit blocks. Then, \dots | [
"for $x_1 \\neq x_2$, $\\Pr[C(x_1) = y_1, C(x_2)=y_2] = \\frac{1}{2^{2\\ell}}$.",
"the size of the key space of $C$ should be at least $(2^{\\ell}!)$.",
"given pairwise independent inputs to $C$, the corresponding outputs are independent and uniformly distributed.",
"$C$ has an order $3$ decorrelation matrix ... | A |
You are given an i.i.d source with symbols taking value in the alphabet $\mathcal{A}=\{a,b,c,d\}$ and probabilities $\{1/8,1/8,1/4,1/2\}$. Consider making blocks of length $n$ and constructing a Huffman code that assigns a binary codeword to each block of $n$ symbols. Choose the correct statement regarding the average ... | [
"It is the same for all $n$.",
"It strictly decreases as $n$ increases.",
"None of the others.",
"In going from $n$ to $n+1$, for some $n$ it stays constant and for some it strictly decreases."
] | A |
Suppose a file system used only for reading immutable files in random fashion. What is the best block allocation strategy? | [
"Linked-list allocation",
"Continuous allocation",
"Index allocation with B-tree",
"Index allocation with Hash-table"
] | A |
What should the minimal length of the output of a hash function be to provide security against \emph{preimage attacks} of $2^{256}?$ | [
"$2^{256}$ bits.",
"$2^{512}$ bits.",
"$256$ bits.",
"$512$ bits."
] | B |
Does the following code snippet contain bugs? If so, which line(s)?
\begin{lstlisting}[language=C,style=c]
void echo() {
char buf[100];
scanf("%s", buf);
printf(buf);
}
\end{lstlisting} | [
"Line 3 has a bug / vuln",
"Line 4 has a bug / vuln",
"There is no bug / vuln in the code snippet",
"Line 1 has a bug / vuln",
"Line 2 has a bug / vuln",
"Line 5 has a bug / vuln"
] | A |
Let $E$ be an elliptic curve. Solving which of the following problems would help you to break Elliptic Curve Diffie-Hellman (ECDH) over $E$? | [
"Let $P,R \\in E$. Given $P$ and $P+R$, compute $R$.",
"Let $P,Q \\in E$. Given $P$ and $Q$, compute the product between $P$ and $Q$, i.e., $P \\times Q$.",
"Let $P \\in E$ and $\\ell \\in \\mathbb{N}$. Given $P$ and $\\ell P$, compute $\\ell$.",
"Find a point which is not on the curve $E$."
] | A |
Select \emph{incorrect} statement. The exhaustive search | [
"can be used to find a secret key of AES.",
"is a brute force attack.",
"is not applicable against perfectly secure cipher.",
"runs in time polynomial in the length of the key."
] | B |
In Ranked Retrieval, the result at position k is non-relevant and at k+1 is relevant. Which of the following is always true?
Hint: P@k and R@k are the precision and recall of the result set consisting of the k top-ranked documents. | [
"P@k-1>P@k+1",
"R@k-1=R@k+1",
"R@k-1<R@k+1",
"P@k-1=P@k+1"
] | A |
Mean Square Error loss: | [
"Minimizing the distance between the predicted point and the true point",
"Maximizing the probability of the correct class",
"Minimizing the score of false classes when they are close, or bigger than, the score of the true class",
"Maximizing the accuracy"
] | A |
For which document classifier the training cost is low and inference is expensive? | [
"for none",
"for kNN",
"for NB",
"for fasttext"
] | B |
In Machine Learning, we want to learn the \textbf{parameters W} for the mapping function f: $y=f(x,W) +\epsilon$ where x is the input, y the output, and $\epsilon$ the error term.\\
(One or multiple answers) | [
"When f: $R \\rightarrow \\{1,..N\\}$, it is a classification task",
"When f: $R^M \\rightarrow \\{1,..N\\}$, it is a classification task",
"When f: $R^M \\rightarrow R$, it is a classification task ",
"When f: $R^M \\rightarrow R$, it is a regression task"
] | B |
Consider the following lexicon \(L\):
bear : V, N
bears : V, N
blue : Adj, N
drink : N, V
drinks : N, V
Nice : Adj, N
When using an order-1 HMM model (using \(L\)) to tag the word sequence:"Nice bears drink blue drinks"does the tag of drink depend on the tag of nice? | [
"yes, because the HMM approach relies on a global maximum.",
"no, the hypotheses make the two tags independent from each other."
] | B |
Which one of these digital signature schemes is \emph{not} based on the Discrete Log problem? | [
"DSA",
"ECDSA",
"Pointcheval-Vaudenay",
"PKCS\\#1v$1.5$"
] | A |
Which of the following primitives \textit{cannot} be instantiated with a cryptographic hash function? | [
"A pseudo-random number generator.",
"A commitment scheme.",
"A public key encryption scheme.",
"A key-derivation function."
] | B |
Tick the \textbf{true} assertion. In a zero-knowledge interactive proof for $L$, \ldots | [
"for any ppt verifier, there is a simulator which for any $x \\in L$ produces a conversation indistinguishable from the original conversation.",
"for any ppt verifier, for some $x \\in L$, any simulated conversation is indistinguishable from the original conversation.",
"the simulator imitates the verifier.",
... | A |
Suppose you have a search engine that retrieves the top 100 documents and
achieves 90% precision and 20% recall. You modify the search engine to
retrieve the top 200 and mysteriously, the precision stays the same. Which one
is CORRECT? | [
"The recall becomes 10%",
"The number of relevant documents is 450",
"The F-score stays the same",
"This is not possible"
] | B |
Suppose that q is density reachable from p. The chain of points that ensure this relationship are {t,u,g,r} Which one is FALSE? | [
"{t,u,g,r} have to be all core points.",
"p and q will also be density-connected",
"p has to be a core point",
"q has to be a border point"
] | A |
Which of the following is WRONG for Ontologies? | [
"Different information systems need to agree on the same ontology in order to interoperate.",
"They help in the integration of data expressed in different models.",
"They give the possibility to specify schemas for different domains.",
"They dictate how semi-structured data are serialized."
] | A |
$\mathrm{GF}(2^k)$ is represented by the set of\dots | [
"polynomials of degree at most $k-1$ with binary coefficients.",
"polynomials of degree at most $k-1$ with coefficients in $\\mathbb{Z}_k$.",
"polynomials of degree at most $2^k$ with coefficients in $\\mathbb{Z}$.",
"polynomials of degree at most $2$ with coefficients in $\\mathbb{Z}_k$."
] | A |
Tick the \textbf{true} statement regarding $\mathsf{GF}(2^k)$. | [
"Addition is performed as bitwise XOR.",
"Multiplication is performed modulo $2^k$.",
"It has order $\\varphi(2^k)$.",
"Its characteristic is $k$."
] | A |
Let $\mathcal{C}$ be a binary $(6,3)$ linear code containing the codewords $\mathbf{x}_1 = 011011$, $\mathbf{x}_2 = 101101$ and $\mathbf{x}_3 = 111000$. True or false: The minimum distance of the code is $d_{\min} = 3$. | [
"True",
"False"
] | A |
Select what statements are true about probabilistic parsing.A penalty will be applied for any wrong answers selected. | [
"The purpose of introducing probabilities at the syntactic level is to enable the parser to choose among different parses of an ambiguous sentence.",
"The probabilities aims at capturing linguistic phenomena that are hard to express in operational terms but can be estimated from linguistic corpora.",
"Probabili... | A |
Tick the \textit{incorrect} assertion. | [
"Plain CBCMAC resists forgery attacks.",
"GCM is a blockcipher mode of operation that provides both confidentiality and authenticity for messages.",
"A message authentication scheme that resists a chosen message forgery attack will also resist a known message forgery attack.",
"HMAC is a message authenticatio... | A |
Tick the \emph{correct} assertion. Assume that $C$ is an arbitrary random permutation. | [
"$\\mathsf{BestAdv}_n(C,C^\\ast)=\\mathsf{Dec}^n_{\\left|\\left|\\left|\\cdot\\right|\\right|\\right|_\\infty}(C)$",
"$\\mathsf{BestAdv}_n(C,C^\\ast)=\\mathsf{Dec}^{n/2}_{\\left|\\left|\\left|\\cdot\\right|\\right|\\right|_\\infty}(C)$",
"$E(\\mathsf{DP}^{C}(a,b)) < \\frac{1}{2}$",
"$\\mathsf{BestAdv}_n(C,C^\... | A |
You want to build a convolutional neural network to distinguish between types of cars in images. Your friend Alice, a biologist, has been working on a network to classify wildlife, which she calls WildNet. She spent several weeks training that network, and made it accessible to you. What can you do with it? | [
"Nothing, wildlife is not the same as cars.",
"I can't reuse any of the weights of any layer, but I can take inspiration from the architecture of WildNet.",
"I can freeze the last few layers, and then remove the early layers and replace it with my own re-learned layers. That way, I can make use of the generic f... | A |
A neural network has been trained for multi-class classification using cross-entropy but has not necessarily achieved a global or local minimum on the training set.
The output of the neural network is $\mathbf{z}=[z_1,\ldots,z_d]^ op$ obtained from the penultimate values $\mathbf{x}=[x_1,\ldots,x_d]^ op$ via softmax $... | [
"One transformation has no effect, the other one decreases the accuracy in some cases (but never increases it).",
"One transformation has no effect, the other sometimes increases and sometimes decreases the accuracy.",
"Neither transformation affects the accuracy.",
"Both transformations decrease the accuracy... | A |
A 128-bit key ... | [
"has 128 decimal digits.",
"is too long for any practical application.",
"provides reasonable security for at least four decades.",
"adresses $n^2$ problem for $n=2^{64}$."
] | A |
Do the functions first and second return the same output for every possible input? def first(x: List[Int]): Int = x.head + first(x.tail) def second(x: List[Int]): Int = x.foldLeft(0)(_ + _) | [
"Yes",
"No"
] | B |
Tick the \textbf{false} statement. The Shannon Encryption Model ... | [
"requires a black-box encryption model.",
"assumes a known input distribution.",
"assumes the key is independent from the message.",
"requires the correctness property $\\Pr[C_K^{-1}(C_K(X))=X]=1$."
] | B |
Tick the \emph{incorrect} statement. When $x\rightarrow+\infty$ \ldots | [
"$x^3 + 2x + 5 = \\mathcal{O}(x^3)$.",
"$\\frac{1}{x^2} = \\mathcal{O}(\\frac{1}{x})$.",
"$2^{\\frac{x}{\\log x}} = \\mathcal{O}(2^x)$.",
"$n^x = \\mathcal{O}(x^n)$ for any constant $n>1$."
] | B |
For binary classification, which of the following methods can achieve perfect training accuracy on \textbf{all} linearly separable datasets? | [
"Decision tree",
"Hard-margin SVM",
"15-nearest neighbors",
"None of the suggested"
] | B |
Select the non-associative operation. | [
"$+$ (addition)",
"$-$ (subtraction)",
"$\\times$ (multiplication)",
"$\\oplus$ (exclusive-or)"
] | A |
Select the \textbf{most accurate} answer. For a hash function to be secure (\textbf{but still efficient}) against collision attacks in 2015, the output length should be\dots | [
"around 80 bits.",
"around 160 bits.",
"around 512 bits.",
"around 1024 bits."
] | A |
Consider an RSA encryption where the public key is published as $(m, e) = (35, 11)$. Which one of the following numbers is a valid decoding exponent? | [
"$11$",
"$7$",
"$5$",
"$17$"
] | A |
Choose the \emph{correct} statement. | [
"$\\mathbb{Z}_n$ is a field $\\Leftrightarrow$ $n$ is a composite number",
"$\\mathbb{Z}_n$ is a field $\\Leftrightarrow$ $\\mathbb{Z}_n^* = \\mathbb{Z}_n$",
"$\\mathbb{Z}_n$ is a field $\\Leftrightarrow$ $n$ is a prime",
"$\\mathbb{Z}_n$ is a field $\\Leftrightarrow$ $\\mathbb{Z}_n^* = \\emptyset$"
] | B |
$\mathbb{Z}_{37}^*$ denotes ... | [
"a field.",
"an additive group.",
"a multiplicative group.",
"a ring."
] | A |
What is the average complexity of exhaustive search when the key is distributed uniformly at random over $N$ keys? | [
"$\\log N$",
"$2^N$",
"$\\frac{N+1}{2}$",
"$\\sqrt{N}$"
] | B |
Which assertion has not been proven? | [
"SAT $\\in P$.",
"SAT is $NP$-complete.",
"SAT $\\in NP$.",
"SAT $\\in IP$."
] | B |
An element of the finite field $\mathrm{GF}(2^8)$ is usually represented by\dots | [
"\\dots one hexadecimal digit.",
"\\dots eight bytes.",
"\\dots two hexadecimal digits.",
"\\dots an irreducible polynomial of degree 8."
] | A |
The Advanced Encryption Standard (AES) is based on arithmetics on\dots | [
"$\\mathrm{GF}(256)$",
"$\\mathbf{Z}_{2^8}^*$",
"$\\mathbf{Q}\\setminus \\{0\\}$",
"$\\mathbf{Z}_{2^8}$"
] | B |
Our task is to classify whether an animal is a dog (class 0) or a cat (class 1) based on the following features:
egin{itemize}
\item $x_1$: height
\item $x_2$: length of whiskers
\item $x_3$: thickness of fur
\end{itemize}
We perform standard normal scaling on the tr... | [
"$w_1 < w_2 < w_3$",
"$w_1 < w_3 < w_2$",
"$w_2 < w_1 < w_3$",
"$w_2 < w_3 < w_1$",
"$w_3 < w_1 < w_2$",
"$w_3 < w_2 < w_1$"
] | A |
Tick all correct answers: | [
"Fuzz testing scales at least to 1'000s of lines of code.",
"Compiler warnings scale to millions lines of code.",
"Formal verification scales at least upto 100'000s of lines of code.",
"Formal verification and concolic execution scale to the same extent."
] | A |
Which of the following statement(s) is/are true? To achieve memory safety for C, ... | [
"pointer arithmetic must be checked/restricted",
"memory deallocation must be replaced by garbage collection",
"all control-flow must be validated against a model",
"a strict specification of program functionality is required",
"the standard library must be formally verified"
] | A |
Let the first four retrieved documents be N N R R, where N denotes a non-relevant and R a relevant document. Then the MAP (Mean Average Precision) is: | [
"1/2",
"5/12",
"3/4",
"7/24"
] | A |
Given a function $f:\left\{ 0,1 \right\}^p \rightarrow \left\{ 0,1 \right\}^q$, given $a\in\left\{ 0,1 \right\}^p$ and $b \in \left\{ 0,1 \right\}^q$, we define $DP^{f}(a,b) = \Pr_{X}[f(X \oplus a) = f(X) \oplus b]$. We have that $\ldots$ | [
"$DP^f(0,b) = 1$ if and only if $b \\not= 0$.",
"$DP^f(a,a) =1$.",
"$\\sum_{a \\in \\{0,1\\}^p} \\sum_{b \\in \\{0,1\\}^q} DP^f(a,b)= 2^p $.",
"when $f$ is a permutation and $p=q$, $DP^f(a,0) = 1$."
] | B |
Let $H$ be a hash function. Collision resistance means that \dots | [
"given $y$, it is hard to find $x$ such that $H(x)=y$",
"given $x$, it is hard to find $y$ such that $H(x)=y$",
"it is hard to find $x_1$ and $x_2\\neq x_1$ such that $H(x_1)=H(x_2)$",
"given $x_1$, it is hard to find $x_2\\neq x_1$ such that $H(x_1)=H(x_2)$"
] | A |
Tick the \emph{false} answer. In a group, the operation\dots | [
"is commutative",
"is associative.",
"has a neutral element.",
"associates an inverse to each value."
] | A |
Select \emph{incorrect} statement. Generic attacks on DES include | [
"time memory tradeof against 2 key Triple DES.",
"collision attack against 3 key Triple DES.",
"meet in the middle attack against 3 key Triple DES.",
"known plaintext attack by Van Oorschot-Wiener agains 2 key Triple DES."
] | A |
What is the difference between C++'s \texttt{static\_cast} and \texttt{dynamic\_cast}? | [
"\\texttt{static\\_cast} does not perform any kind of runtime check, while \\texttt{dynamic\\_cast} performs runtime checks on the validity of the cast.",
"\\texttt{static\\_cast} is faster but less safe than \\texttt{dynamic\\_cast}.",
"\\texttt{static\\_cast} can only be applied to static classes whereas \\te... | B |
When computing PageRank iteratively, the computation ends when... | [
"The difference among the eigenvalues of two subsequent iterations falls below a predefined threshold",
"The norm of the difference of rank vectors of two subsequent iterations falls below a predefined threshold",
"All nodes of the graph have been visited at least once",
"The probability of visiting an unseen... | A |
Let $S$ be a random variable taking values in $\{a,b,c,d,e\}$ with the following probabilities. $$egin{array}{|c|c|c|c|c|c|} \hline & a & b & c & d & e \ \hline p_S(\cdot) & 1/3 & 1/3 & 1/9 & 1/9 & 1/9\ \hline \end{array}$$ Let $\Gamma_D$ be the $D$-ary Huffman code for $S$. Let $L(S,\Gamma_D)$ be the average codeword... | [
"False",
"True"
] | B |
KEM \dots | [
"stands for Keyless Encryption Mechanism.",
"is a Korean encryption mechanism.",
"is a symmetric-key algorithm.",
"is a public-key algorithm."
] | B |
Select the \emph{incorrect} statement. Pedersen Commitment is | [
"unconditionally hiding.",
"computationally binding.",
"based on the hardness of the discrete logarithm problem.",
"based on DSA."
] | B |
Tick the \textbf{incorrect} assertion. Let $H:\left\{ 0,1 \right\}^*\rightarrow\left\{ 0,1 \right\}^n$ be a hash function. | [
"We can use $H$ to design a commitment scheme.",
"We can use $H$ to design a key derivation function.",
"Finding $x,y\\in\\left\\{ 0,1 \\right\\}^*$ such that $x\\neq y$ and $h(x) = h(y)$ can be done in $O(2^{n/2})$ time.",
"Given $x\\in\\left\\{ 0,1 \\right\\}^*$, finding a $y \\in \\left\\{ 0,1 \\right\\}^*... | B |
Consider a matrix factorization problem of the form $\mathbf{X}=\mathbf{W Z}^{\top}$ to obtain an item-user recommender system where $x_{i j}$ denotes the rating given by $j^{\text {th }}$ user to the $i^{\text {th }}$ item . We use Root mean square error (RMSE) to gauge the quality of the factorization obtained. Selec... | [
"Given a new item and a few ratings from existing users, we need to retrain the already trained recommender system from scratch to generate robust ratings for the user-item pairs containing this item.",
"Regularization terms for $\\mathbf{W}$ and $\\mathbf{Z}$ in the form of their respective Frobenius norms are a... | A |
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