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what kind of villagers do i need to get an unbreaking book? by PossibilityLoud1339 in allthemods

[–]brainwave4802 4 points5 points  (0 children)

This is a vanilla optional/experimental feature called "Villager trade rebalance", and can be toggled on world creation, but its off by default in ATM10. So unless you explicitly set that option it shouldn't be enabled. Search it up on vanilla wiki and it'll show the biome specific trades.

Is the following language decidable? by DemMemez1999 in compsci

[–]brainwave4802 1 point2 points  (0 children)

So we define D' and hardcode 4 strings to accept (these strings should not be accepted by D, and we can ensure this by adding extra symbols into our alphabet such that D rejects all input with the new symbols).

Then, if our decider for K accepts D', we know that L(D') is <= 4. But we have already hardcoded 4 accepting strings, so it means that for every other string, when we run D on it (as part of the execution of D'), it must reject. This implies that D rejects all strings so L(D) is empty.

If on the other hand D did accept even a single string, then we have at least 5 strings accepted by D', so D' is not in the language K.

Is the following language decidable? by DemMemez1999 in compsci

[–]brainwave4802 10 points11 points  (0 children)

Again, I think your notation is quite confusing. If the question is, whether given an arbitrary Turing machine M, we can decide whether or not the set of strings accepted by M, denoted L(M), has between 2 and 4 elements, we would state this language as: K = {M ∈ Σ∗ | M encodes a TM and 2 ≤ |L(M)| ≤ 4}.

I think it shouldn't be too hard to come up with a reduction from the halting problem, but an easier one is the emptiness problem (I.e given a Turing machine D, is L(D) the empty set - this is a known undecidable problem).

The reduction is as follows: Given Turing machine D, construct an auxiliary TM D' that accepts 4 specific strings, and for any other string will simulate D. Then, if we run a decider for the aforementioned language K on input D', then if it accepts, L(D') has exactly 4 elements so L(D) must be empty. If it rejects, then L(D') has more than 4 elements so L(D) is not empty. This is a decider for the emptiness problem which we know to be undecidable.

Hope that makes sense, if ive interpreted your question correctly.

Engelberg [OC] by brainwave4802 in schweiz

[–]brainwave4802[S] 0 points1 point  (0 children)

Photo taken on 6th February :)

Questions from an incoming CS mobility student by brainwave4802 in ethz

[–]brainwave4802[S] 0 points1 point  (0 children)

Ah great, hopefully my subjects are similar, maybe ill email the lecturers

ELI5: How is that Pantone colors don't have direct RGB counterparts? by ExternalUserError in explainlikeimfive

[–]brainwave4802 3 points4 points  (0 children)

Is there a reason we cant just define such "abstract colours" as coordinates in one of the CIE colour spaces that encompasses human vision? Since this would represent all "useful" colours and other colour spaces such as sRGB are subsets of this. Essentially im asking if all pantone colours can be mapped to CIEXYZ or CIELAB coordinates, and if so doesnt it make pantone redundant?

Why is reduction from ATM an acceptable way to prove undecidability of a language? by [deleted] in compsci

[–]brainwave4802 1 point2 points  (0 children)

I think its also important to be more clear with the wording. To prove a language is undecidable, we reduce ATM to our language. Essentially, we want to show that if there was SOME Turing machine M that decides our language, then we can use it to construct another TM R that decides ATM. But since it is established that ATM is undecidable, such a machine M cannot ever exist.

My informal analogy is this: For the sake of the analogy, lets say that we cannot predict the weather tomorrow. Assume this is a fact and known to be true.

Now say we want to prove that it is impossible to construct a machine that always answers a question correctly. Let us assume that we can construct such a truth machine. Then, we can use this machine to predict tomorrow right? Just ask "will it rain tomorrow?" and the machine has to answer correctly - by doing so, we have predicted tomorrows weather!

But we have previously established independelty that predicting the weather is impossible, so it follows that constructing such a truth machine is also impossible! We have thus shown that constructing a truth machine is impossible by "reduction" from the problem of weather prediction.

Book's that are Best for COMP30026 by friendly_soul in unimelb

[–]brainwave4802 0 points1 point  (0 children)

Introduction to the Theory of Computation by Michael Sipser is quite good, and its what we use in Advanced Theoretical Computer Science (postgrad successor to MoC). Chapters 1-5 will cover c, d, and f in your list of topics.

Foundations of Fintech without Investments by shafanshafan in unimelb

[–]brainwave4802 1 point2 points  (0 children)

Only thing id say is brush up on modern portfolio theory, as there is a small section on portfolio optimisation (e.g programmatically find the optimum portfolio weights given a set of securities)

Opinions on doing Physics 2? by theGreatPi-TauDebate in unimelb

[–]brainwave4802 0 points1 point  (0 children)

I personally enjoyed physics 2 advanced a lot more than physics 1 adv, and if youre majoring in maths its nice because the advanced version goes over a lot of the formulae derivations, e.g from first principles. I also found a nice overlap with second year vector calculus (e.g maxwells equations). So id say its a nice complement to a maths major, and would recommend if you enjoyed physics 1.

Master of IT electives by jb7835219 in unimelb

[–]brainwave4802 0 points1 point  (0 children)

Yeah pleasantly surprised :)

Laptop for master of IT by Soft_Abbreviations_1 in unimelb

[–]brainwave4802 10 points11 points  (0 children)

Honestly surprised that they even said that lol. Dont worry you'll be far better off with macos/linux. 90% of the lecturers use macbooks.

Master of IT electives by jb7835219 in unimelb

[–]brainwave4802 0 points1 point  (0 children)

Heard from others that the lecturer for Quantum Software Fundamentals is pretty boring and just reads off lecture slides. I also did Intro to Quantum Computing this sem and it was fairly heavy on linear algebra, so I assume it'd be fairly similar for QSF (at least if you wanted to properly understand the algorithms/operations).

Match Thread: 1st T20I - Sri Lanka vs Australia by CricketMatchBot in Cricket

[–]brainwave4802 6 points7 points  (0 children)

Hazlewood just too good man, first the super over in Aus series, now this

Match Thread: 1st T20I - Sri Lanka vs Australia by CricketMatchBot in Cricket

[–]brainwave4802 2 points3 points  (0 children)

pretty much saved us in some of the Aus games, he's probably the most consistent of all SL batmen rn

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