What is Rules: Definition and 536 Discussions

International rules football (Irish: Peil na rialacha idirnáisiunta; also known as international rules in Australia and compromise rules or Aussie rules in Ireland) is a team sport consisting of a hybrid of football codes, which was developed to facilitate international representative matches between Australian rules football players and Gaelic football players.
The first tour, known as the Australian Football World Tour, took place in 1967, with matches played in Ireland, the United Kingdom, and the United States. The following year, games were played between Australia and a touring County Meath Gaelic football team, Meath being the reigning All-Ireland senior football champions. Following intermittent international tests between Australia and Ireland, the International Rules Series between the senior Australian international rules football team and Ireland international rules football team has been played intermittently since 1984, and has generally been a closely matched contest. The sport has raised interest and exposure in developing markets for Gaelic and Australian football and has been considered a development tool by governing bodies of both codes, particularly by the AFL Commission.
International rules football does not have any dedicated clubs or leagues. It is currently played by men's, women's, and junior teams only in tournaments or Test matches.

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  1. paulb203

    B Why are the division rules for surds the way they are?

    Why does, 4√64÷2√4 =2√16 ? I can see the method (4÷2=2, √64÷√4=√16) But why is it not; 4 times √64 divided by 2 times √4 (as per BODMAS) i.e, 4 times 8 divided by 2 times 2, which = 32 Nb. When I put it into my calculator that way it gives 32 as the answer (4*√64÷2√4)
  2. S

    Vietnamese traditional wrestling - the rules?

    What are the rules for Vietnamese traditional wrestling? I find online sources in English that say a wrestler loses if that wrestler's back touches the ground or if both the wrestler's feet leave the ground. With that in mind, there are many videos of such wrestling online that I don't...
  3. Maarten Havinga

    Strict forum rules vs learning science

    This thread is about whether strictly and always applying the forum rules allow for the whole picture of exact science. For every one of the rules there is a good scientific reason, the question is not about the quality of the rules but rather about the 'fruits' of applying them strictly. I...
  4. Vanilla Gorilla

    B Transformation Rules For A General Tensor M

    So, I've been watching eigenchris's video series "Tensors for Beginners" on YouTube. I am currently on video 14. I am a complete beginner and just want some clarification on if I'm truly understanding the material. Basically, is everything below this correct? In summary of the derivation of the...
  5. S

    I Selection Rules for a Diatomic Molecule?

    Hello! I have a question about selection rules and electronic transitions of a diatomic molecule: I can't find a good explanation about that, and there's so much confusion about the right rules to use. I studied that on Bransden-Joachain's "Physics of atoms and molecules", but there (to whom...
  6. mcastillo356

    I Some questions on l'Hôpital rules

    Hi, PF Got questions to start with: ¿some casual background about these Rules?; ¿are them two, as the textbook says?. https://en.wikipedia.org/wiki/L%27H%C3%B4pital%27s_rule (only one statement found) Here goes the first, from "Calculus, 7th ed, R, Adams, C. Essex" THEOREM 3 The first...
  7. Fady Megally

    I Second derivative, chain rules and order of operations

    So the chain rule for second derivatives is $$ \frac {d^2 y} {d t^2} = \frac{d}{dx}(\frac {dy} {dx}) \cdot \frac {dx} {dt} \cdot \frac {dx} {dt} + \frac {dy} {dx} \cdot \frac {d^2 x} {d t^2} = \frac{d^2 y}{d x^2} \cdot (\frac {dx} {dt})^2 + \frac {dy} {dx} \cdot \frac {d^2 x} {d t^2}$$ Today I...
  8. ohwilleke

    I New Naming Rules for Exotic Hadrons at the LHC: LHCb Collaboration Paper (2022)

    The LHCb collaboration at the Large Hadron Collider has developed a new set of rules for naming composite particles bound by the strong force (i.e. hadrons) that are contemplated by existing rules for naming them. This has significant practical relevance to anyone dealing with high energy hadron...
  9. nomadreid

    Selection rules in electron transitions

    Not sure if this belongs in Chemistry or Physics. Even less sure if I understand the selection rules for electron transition correctly; hence this question. So I would be grateful for someone to please correct the following: Letting n and m be energy levels An electron that absorbs a photon...
  10. A

    I Arithmetic representation of symbols according to certain rules

    Hi, Suppose I am given a sequence of special symbols and I want to produce the next sequence of symbols according to certain rules that transform one symbol into one or more symbols. They are 10 symbols in total, say; A, B, C, D, E, F, G, H, I, J The rules are: A transformed into B and it is...
  11. S

    MHB Are the inference rules of propositional calculus tautologies?

    Are the inference rules of propositional calculus tautologies ,yes or no
  12. user366312

    Admissions European PhD Application Rules: Incomplete Degree Programs from Poland

    I already have an MSc from outside the EU. But, I also have an incomplete CS degree from Poland which I dropped out of. European Ph.D. schools often ask for a CV, not "all the transcript from all the attended programs" as they ask in North America. Therefore, can I skip the information...
  13. samy4408

    Question about the rules of thermodynamics

    Hello , we learned in thermodynamics that to calculate ΔHr °(of the reaction ) using ΔHf °(standard heat of formation ), we have to respect that ΔHf °=ΔHr ° of a reaction forming 1 mol of compound from pure elements in their most stable form at standard state . the problem is when we want to...
  14. E

    I Schwartz derivation of the Feynman rules for scalar fields

    Hi everyone, In his book "Quantum field theory and the standard model", Schwartz derives the position-space Feynman rules starting from the Schwinger-Dyson formula (section 7.1.1). I have two questions about his derivation. 1) As a first step, he rewrites the correlation function as $$...
  15. E

    A HQET Feynman Rule: QCD Interaction Vertex Explained

    Several texts state the vertex HQET Feynman rule as : igTijvμ\frac{1}{1+\slashed{v}} with the reasoning for vμ presented as being due to the QCD interaction vertex being between two heavy quark propagators, which are \frac{1+\slashed{v}}{2v.k}, giving ...
  16. shivajikobardan

    Comp Sci Which knowledge are rules of thumb: Factual knowledge or heuristic?

    really confused at this. which is rule of thumb? some slides say heuristic is rule of thumb whereas others say factual knowledge is rule of thumb. the context of this is architecture/block diagram of expert system. i think heuristic knowledge should be called rule of thumb. but i am not sure.
  17. ergospherical

    I Parity Selection Rules: I'm Confused

    I'm confused by the discussion in section §30 (Parity of a state), page 98 of Landau's QM. The functions ##\psi_u## and ##\psi_g## are odd an even states respectively. If ##f## is a true scalar, then it should remain unchanged by inversion of the co-ordinates. Writing ##q' = -q##, then its...
  18. P

    I What's the field strength and pattern rules for bar magnets attached?

    The attached probem tricked me because the answer is apparently D and not A. Presumably because the magnetic field is weaker with 2 bar magnets joined N/S compared to a single bar magnet. So this seems to be a gap in my knowledge as to the resulting strengths of magnets joined together. Are...
  19. M

    Feynman rules and the tree level cross section of two scalar fields

    Hi there. I'm trying to solve the problem mentioned above, the thing is I'm truly lost and I don't know how to start solving this problem. Sorry if I don't have a concrete attempt at a solution. How do I derive the Feynman rules for this Lagrangian? What I think happens is that in momentum...
  20. kyphysics

    With College Starting Up in Week or Two, How Are Your Campus COVID Rules?

    I know lots of people here are in undergrad or graduate school (some maybe even as faculty). I'm curious how your institution is handling the return-to-school process in the midst of COVID/Delta? Are you at 100% capacity? Maybe 50% (with a hybrid online mix, for example)? Will masks and/or...
  21. S

    I Orbitals and selection rules in a synchrotron

    What orbitals are occupied in a synchrotron, and which selection rules limit charged particles in a synchrotron? A Schrödinger hydrogen atom is not actually the Bohr atom, but the Bohr theory gives correct energies (but not transition probabilities). Why? Because in a hydrogen-like atom, 2s...
  22. B

    I It seems that the eigenvalue problem rules out the possibility of E=0?

    Since the eigenvalue problem can't distinguish between a non-existent wavefunction (and therefore a non-existent particle), and the energy being zero. This is the next thing that has started bothering me on my journey to understand quantum mechanics. For example, in the algebraic derivation of...
  23. Steve Rogers

    Transformation rules for vielbein and spin connection

    I am taking a course on General Relativity. Recently, I was given the following homework assignment, which reads > Derive the following transformation rules for vielbein and spin connection: $$\delta e_a^\mu=(\lambda^\nu\partial_\nu e_a^\mu-e_a^\nu\partial_\nu\lambda^\mu)+\lambda_a^b e_b^\mu$$...
  24. E

    B Slide rules rule

    Digression, but what on Earth is that ruler thing he's using to calculate products at 14:10 and 15:40? Edit: I found it, it's called a "slide rule": https://www.math.utah.edu/~alfeld/sliderules/
  25. JD_PM

    Deriving Feynman rules out of a generating functional

    To approach the problem I first studied section 1.3 and, more importantly, 1.4 of Osborn's notes. We first need to compute ##\partial_j \omega_i (x)## and ##\omega_i (x)\omega_i (x)## \begin{equation*} \partial_j \omega_i (x) = \delta_{ij} + \underbrace{\partial_j (g_{ilm})}_{=0}x_l x_m +...
  26. M

    MHB Logic Proof With Rules of Replacement

    Not sure if this is an allowed post, as it is not technically math but I'm trying to work through the below proof. If workers have a fundamental right to a job, then unemployment will be virtually nonexistent but job redundancy will become a problem. If workers have no fundamental right to a...
  27. JD_PM

    I Understanding how to derive the Feynman rules out of the path integral

    I am studying interacting scalar fields (from Osborn) using the path integral approach. We define the functional integral \begin{equation*} Z[J] := \int d[\phi] e^{iS[\phi] + i\int d^d x J(x) \phi(x)} \tag{1} \end{equation*} The idea is to differentiate ##Z[J]## with respect to ##J## and end...
  28. Will26040

    Engineering Tuning Rules for Lag Dominated FOPDT (first-order plus deadtime) model

    I am trying to find an alternative tuning rule for use with the transfer function specified. Please could someone help by pointing me in the right direction, thanks. Process transfer function: ## \frac {27e^{-3s}} {30s+1} ## Also, am I right in thinking that this process transfer function is...
  29. JD_PM

    Feynman Rules on ##\phi^3, \phi^4## theory

    Let us first take the S-matrix expansion (i.e. Dyson's formula) \begin{align*} S_{fi}&=\langle f | T \left\{ \exp\left( i\frac{\lambda_3}{3!}\int d^4 x :\phi \phi \phi (x) : + i\frac{\lambda_4}{4!}\int d^4 x :\phi \phi \phi \phi (x) : \right) \right\}| i \rangle \\ &= \langle f | i...
  30. JD_PM

    I Feynman rules on a ##\phi^3, \phi^4## theory

    The weakly coupled theory is given by the Lagrange density$$\mathcal{L}=\mathcal{L}_0 + \mathcal{L}_I=\frac 1 2 \partial_{\mu} \phi \partial^{\mu} \phi - \frac{m^2}{2} \phi^2 - \frac{\lambda_3}{3!} \phi^3 - \frac{\lambda_4}{4!} \phi^4 \tag{1}$$ Where \begin{equation*} \mathcal{L}_0 = \frac...
  31. M

    MHB De Morgan Rules - Logical statements

    Hey! 😊 I have proven the following properties: (i) $(a\Rightarrow b)\iff (\neg b\Rightarrow \neg a)$ (ii) $[(a\Rightarrow b)\land (b\Rightarrow c)]\Rightarrow (a\Rightarrow c)$ (iii) $[a\land (a\Rightarrow b)]\Rightarrow b$ At the second part of the exercise we have to show the de Morgan...
  32. M

    MHB Prove that the statement is always true using the rules of boolean algebra

    Hey! 😊 I want to prove by using the rules of boolean algebra that the following statement is always true $$\{b\land [\neg a\Rightarrow \neg b]\} \Rightarrow a$$ Since we have to use the rules of boolean algebra, we cannot use the truth table, right? Could you give me a hint how we could...
  33. E

    The NMR Selection Rules: Understanding Allowed Spin State Transitions

    For simplicity I only take a system of two interacting spin-##1/2## nuclei. If the spins have quantum numbers ##m_1## and ##m_2## respectively when in a certain state, then the energy of that particular state is$$E_{m_1m_2} = m_1 v_{0,1} + m_2 v_{0,2} + m_1 m_2 J_{12}$$where ##v_{0,1}## and...
  34. dRic2

    I Understand selection rules in ##\beta##-decay/EC

    I'm not very familiar with this topic so I quickly went through some introductory books on nuclear physics and read the chpater about beta decay. What I don't understand looking at this graph is the following: Why is the direct decay to ground state absolutely forbidden ? If you take a 1st order...
  35. L

    MHB Summation and product notation rules

    As per the image, I am supposed to select all the valid statements. Apparently I'm only partially correct, and so I took another look at the statements. I believe the third statement is wrong, since c * (a_m*a_{m+1}*a_{m+2}*...*a_n) =/= (c*a_m)(c*a_{m+1})(c*a_{m+2})*...*(c*a_n) Thus there...
  36. Fervent Freyja

    Rules and regulations for TV commercials

    Does anyone happen to know right off if it’s allowable to run a still ad (single image) for 30 seconds straight as a TV commercial in the US? I’ve never seen this. Have any of you? I tried to look it up but couldn’t find a clear answer. Not very familiar with the rules and regulations for TV...
  37. tomdodd4598

    I QED - ordering of Feynman diagram rules

    Hey there, In QED, we often have Feynman diagrams involving various numbers of non-commuting components, such as for the one-loop vertex correction (Peskin & Schroeder, page 189): The diagram this integral corresponds to is: How do we choose which order to put the propagators and vertex...
  38. E

    B Mapping between rules of classical vs QM probability?

    Apologies in advance for my ignorance, I don't really have a reference to consult and Google hasn't been too helpful! In standard probability theory there are a few common useful formulae, e.g. for two events ##S## and ##T## $$P(S\cup T) = P(S) + P(T) - P(S\cap T)$$ $$P(S \cap T) = P(S) \times...
  39. Mikaelochi

    I Intro to Symbolic Logic: Replacement Rules

    Basically the problem starts with these given premises: 1. ~ (A ∨ (B⊃T)) 2. (A ⋅ C) ∨ (W ⊃ ~D) 3. ~(P ∨ T) ⊃ D 4. ~P ≡ ~(T ⋅ S) And from these premises, I must prove ∴ ~W. This is what I have done so far: 5. (~P ⊃ ~(T ⋅ S)) ⋅ (~(T ⋅ S) ⊃ ~P) B.E. 4 6. ~P ⊃ ~(T ⋅ S)...
  40. nmsurobert

    Kirchhoff's Rules for analyzing this circuit with batteries and resistors

    Summary:: Choosing the direction of the loop and the current I am attempting to work out Example 1 in the link provided. https://courses.lumenlearning.com/physics/chapter/21-3-kirchhoffs-rules/ When solving for loop aefgh, I get: I1R1-I3R3-I3r2-E2 =0 I chose the current to continue to move...
  41. Wrichik Basu

    A IceCube rules out last SM explanation of ANITA’s anomalous neutrinos

    Quoting from IceCube Observatory's webpage, (Emphasis added.) The paper, available on arXiv, has been submitted to The Astrophysical Journal. I haven't read through the paper yet, but if this detection cannot be explained by the Standard Model, what could possibly be the cause? Is there any...
  42. E

    MHB Rules of Inference: Get Help with Hypothesis 1 & 2

    Hi, I am havinga bit of challenge with the following question. What seems confusing to me is th relationship between hypothesis 1 and 2. I will appreciate all help.
  43. Diracobama2181

    Selection Rules (Time Dependent Perturbation Theory)

    I suppose my question is, since X commutes for H, does this mean that the selection rules are $$<n',l',m'|X|n,l,m>=0$$ unless $$l'=l\pm 1$$ and $$m'=m\pm 1$$, as specified in Shankar?
  44. F

    I What is the proof of the rules of significant figures?

    Please prove the rules of significant figures. I do not know why when multiplying and dividing we have to retain the same number of significant figures as in the number with the least of them.
  45. R

    I Hund's rules and Pauli's principle

    So as I can see from the literature there are two "methods" on how to apply Hund's rules to determine the ground state of an electron configuration. Method 1: One determines all possible states due to Pauli's principle (wave function must be totally antisymmetric) using angular momentum...
  46. M

    Need an exhaustive list of Vibration-Diagnostic Rules

    I am a free-lance Software developer. Recently, I got a big project in my very 2nd assignment where I need to develop a Vibration Analysis Software for condition monitoring of some heavy motors. One of the "Terms & Conditions" of the project is that there must be at least 200 pre-definded...
  47. J

    B Questions Regarding the Fundamental Rules of Error Analysis

    (A)My textbook states the following : (1) The example explaining the italicised statement is rather confusing. My understanding of the statement is that we need to include one extra significant figure than what the relevant rule requires us to round off to, for intermediate...
  48. B

    A LS vs jj couplings and their selection rules

    Two questions, where the 1st is related to previous discussion regarding thes couplings: The selection rules for LS coupling is quite clear - it's based on calculating the compatible electric dipole matrix element. However, in the case of jj coupling we end up with different selection rules...
  49. S

    I Main Sequence Rules: Definition & Interpretation

    When viewing an HR diagram, the main sequence curve is apparent, and the general shape of it is obvious. However, in this truncated version, it's unclear to me exactly which stars should be considered main sequence. I've added a shaded grey area as what I think I should count as main sequence...