## Imitation Games – Avi Wigderson

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If you wish to skip the introduction the talk starts at 5.20. The talk itself lasts roughly an hour, with the last ca. 20 minutes devoted to Q&A – that part is worth watching as well.

Some links related to the talk below:

Theory of computation.

Turing test.

COMPUTING MACHINERY AND INTELLIGENCE.

Probabilistic encryption & how to play mental poker keeping secret all partial information Goldwasser-Micali82.

Probabilistic algorithm

How To Generate Cryptographically Strong Sequences Of Pseudo-Random Bits (Blum&Micali, 1984)

Randomness extractor

Dense graph

Periodic sequence

Extremal graph theory

Szemerédi’s theorem

Green–Tao theorem

Szemerédi regularity lemma

New Proofs of the Green-Tao-Ziegler Dense Model Theorem: An Exposition

Calibrating Noise to Sensitivity in Private Data Analysis

Generalization in Adaptive Data Analysis and Holdout Reuse

Book: Math and Computation | Avi Wigderson

One-way function

Lattice-based cryptography

## Shock waves and gamma-ray bursts from neutron star mergers – Andrei Beloborodov

Some links related to stuff discussed in the lecture/talk:

GW170817.

Superluminal motion of a relativistic jet in the neutron starmerger GW170817 (Mooley et al., 2018).

GRB 170817A Associated with GW170817: Multi-frequency Observations and Modeling of Prompt Gamma-ray Emission (Pozanenko et al., 2018).

Lorentz factor.

Gamma-ray burst progenitors.

Kilonova.

ResearchGate download link: A First-principle Simulation of Blast-wave Emergence at the Photosphere of a Neutron Star Merger (Lundman & Beloborodov, 2020).

Adiabatic index.

Shock waves in astrophysics.

Diffusive Shock Acceleration: the Fermi Mechanism.

Inverse Compton scattering.

## Designing Fast and Robust Learning Algorithms – Yu Cheng

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Some links related to the lecture’s coverage:

Recommender system.

Collaborative filtering.

Matrix completion.

Non-Convex Matrix Completion Against a Semi-Random Adversary (Cheng & Ge, 2018).

Singular value decomposition.

Spectral graph theory.

Spectral Sparsification of Graphs (Spielman & Teng).

Cut (graph theory).

Split (graph theory).

Robust statistics.

Being Robust (in High Dimensions) Can Be Practical (Diakonikolas et al).

High-Dimensional Robust Mean Estimation in Nearly-Linear Time (Cheng, Diakonikolas and Ge).

## Neutron Stars – Victoria Kaspi

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I’ve read *Springer* books – well, *a* book – about pulsars in the past and this is certainly not the first post here on this blog covering these topics, yet I definitely found this lecture hard to follow. It’s highly technical, but occasionally quite interesting.

Some links related to the lecture coverage:

Coherence time.

Coherence (physics).

Pulsar timing and its applications (Manchester 2018).

NE2001. I. A new model for the galactic distribution of free electrons and its fluctuations (Cordes and Lazio).

Pulsar Timing.

Supplementary parameters in the parameterized post-Keplerian formalism.

Shapiro time delay.

Fonseca et al. 2014.

Hulse–Taylor binary.

PSR J0737−3039.

Spin–orbit coupling.

Tests of general relativity – Binary pulsars.

Relativistic Spin Precession in the Double Pulsar (Breton et al. 2008).

PSR J1614−2230.

PSR J0348+0432.

Scalar–tensor theory.

A Massive Pulsar in a Compact Relativistic Binary (Antoniadis et al. 2013).

The strong equivalence principle.

Nordtvedt effect.

PSR J0337+1715.

A millisecond pulsar in a stellar triple system (Ransom, Archibald et al. 2014).

Millisecond pulsar (recycled pulsar).

A comprehensive study of binary compact objects as gravitational wave sources: Evolutionary channels, rates, and physical properties (Belczynski et al. 2002).

Relativistic binary pulsars with black-hole companions (Pfahl et al. 2005).

Pulsar timing array.

PALFA (Pulsar Arecibo L-band Feed Array) Survey.

Green Bank North Celestial Cap (GBNCC) Survey.

## The Shapes of Spaces and the Nuclear Force

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This one was in my opinion a great lecture which I enjoyed watching. It covers some quite high-level mathematics and physics and some of the ways in which these two fields intersected in a specific historical research context; however it does so in a way that will enable many people outside of the fields involved to be able to follow the narrative reasonably easily.

Some links related to the lecture coverage:

Topological space.

Topological invariant.

Topological isomorphism.

Dimension of a mathematical space.

Metrically topologically complete space.

Genus (mathematics).

Quotient space (topology).

Will we ever classify simply-connected smooth 4-manifolds? (Stern, 2005).

Nuclear force.

Coulomb’s law.

Maxwell’s equations.

Commutative property.

Abelian group.

Non-abelian group.

Yang–Mills theory.

Soliton.

Instanton.

Michael Atiyah.

Donaldson theory.

Michael Freedman.

Topological (quantum) field theory.

Edward Witten.

Effective field theory.

Seiberg–Witten invariants.

“Theoretical mathematics”: toward a cultural synthesis of mathematics and theoretical physics (Jaffe & Quinn, 1993).

Responses to “Theoretical mathematics: toward a cultural synthesis of mathematics and theoretical physics (Atiyah et al, 1994).

## Learning Phylogeny Through Simple Statistical Genetics

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From a brief skim I concluded that a lot of the stuff Patterson talks about in this lecture, particularly in terms of the concepts and methods part (…which, as he also alludes to in his introduction, makes up a substantial proportion of the talk), is included/covered in this Ancient Admixture in Human History paper he coauthored, so if you’re either curious to know more, or perhaps just wondering what the talk might be about, it’s probably worth checking it out. In the latter case I would also recommend perhaps just watching the first few minutes of the talk; he provides a very informative outline of the talk in the first four and a half minutes of the video.

A few other links of relevance:

Martingale (probability theory).

GitHub – DReichLab/AdmixTools.

Human Genome Diversity Project.

Jackknife resampling.

Ancient North Eurasian.

Upper Palaeolithic Siberian genome reveals dual ancestry of Native Americans (Raghavan et al, 2014).

General theory for stochastic admixture graphs and F-statistics. This one is only very slightly related to the talk; I came across it while looking for stuff about admixture graphs, a topic he does briefly discuss in the lecture.

## A recent perspective on invariant theory

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Some time ago I covered here on the blog a lecture with a somewhat technical introduction to invariant theory. Even though I didn’t recommend the lecture, I do recommend that you don’t watch the lecture above without first knowing the sort of stuff that might have been covered in that lecture (for all you know, that is), as well as some other lectures on related topics – to be more specific, to get anything out of this lecture you need some linear algebra, you need graph theory, you need some understanding of group theory, you need to know a little about computational complexity, it’ll probably help if you know a bit about invariant theory already, and surely you need some knowledge of a few other topics I forgot to mention. One of the statements I made about the introductory lecture to which I linked above also applies here: “I had to look up a lot of stuff to just sort-of-kind-of muddle along”.

Below some links to stuff I looked up while watching the lecture:

Algebraically closed field.

Reductive group.

Rational representation.

Group homomorphism.

Morphism of algebraic varieties.

Fixed-point subring.

Graph isomorphism.

Adjacency matrix.

Group action (mathematics).

General linear group.

Special linear group.

Alternating minimization, scaling algorithms, and the null-cone problem from invariant theory. (Bürgisser, Garg, Oliveira, Walter, and Wigderson (2017))

Noether normalization lemma.

Succinct data structure. (This link is actually not directly related to the lecture’s coverage; I came across it by accident while looking for topics he *did* talk about and I found it interesting, so I decided to include the link here anyway)

Characteristic polynomial.

Matrix similarity.

Monomial.

Associative algebra.

Polynomial degree bounds for matrix semi-invariants (Derksen & Makam, 2015).

Semi-invariant of a quiver.

## On the possibility of an instance-based complexity theory

…

Below some links related to the lecture’s coverage:

Computational complexity theory.

Minimum cut.

2-satisfiability.

3-SAT.

Worst-case complexity.

Average-case complexity.

Max-Cut.

Karp’s 21 NP-complete problems.

Reduction (complexity).

Levin’s Universal search algorithm – Scholarpedia.

Computational indistinguishability.

Circuit complexity.

Adversarial Perturbations of Deep Neural Networks.

Sherrington–Kirkpatrick model.

Equivalence class.

Hopkins (2018).

Planted clique.

SDP (Semidefinite programming).

Jain, Koehler & Risteski (2018): Mean-field approximation, convex hierarchies, and the optimality of correlation rounding: a unified perspective.

Structural operational semantics (SOS).

## Cardiology: Diabetes Mellitus

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Despite the title this is mainly a pharmacology lecture. It’s a bit dated, but on the other hand the action mechanism of a major drug class usually doesn’t change dramatically in a semi-decade, so the fact that the lecture is a few years old I don’t think is that much of a problem. This is not in my opinion a great lecture, but it was worth watching.

A few random links related to topics covered in the talk:

Thiazolidinedione.

PPAR agonist.

Pioglitazone.

Dipeptidyl peptidase-4 inhibitor.

Glucagon-like peptide-1 receptor agonist.

Pregnancy categories.

Alpha-glucosidase inhibitor.

Sulfonylurea.

SGLT2 inhibitor.

Pramlintide.

## Successes and Challenges in Neural Models for Speech and Language

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Some links related to the coverage:

Speech recognition.

Machine translation.

Supervised learning.

Parsing.

Context-free grammar.

Kernel Approximation Methods for Speech Recognition.

Convolutional neural network.

Dependency parsing | NLP-progress.

Natural Language Processing (Almost) from Scratch (Collobert et al.).

A Fast and Accurate Dependency Parser using Neural Networks (Chen and Manning, 2014).

Question answering.

Natural Questions: a Benchmark for Question Answering Research (Kwiatkowski et al.)

Attention Is All You Need (Vaswani et al. 2017).

Softmax function.

BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding (Devlin et al.).

## Reproducible, Reusable, and Robust Reinforcement Learning

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This pdf was created some time before the lecture took place, but it seems to contains all the slides included in the lecture – so if you want a short version of the talk I guess you can read that. I’ve added a few other lecture-relevant links below.

REPRODUCIBILITY, REPLICABILITY, AND GENERALIZATION IN THE SOCIAL, BEHAVIORAL, AND ECONOMIC SCIENCES (Bollen et al. 2015).

1,500 scientists lift the lid on reproducibility (Nature).

Reinforcement learning.

AlphaGo. Libratus.

Adaptive control of epileptiform excitability in an in vitro model of limbic seizures (Panuccio, Guez, Vincent, Avoli and Pineau, 2013)

Deep Reinforcement Learning that Matters (Henderson et al, 2019).

Policy gradient methods.

Hyperparameter (machine learning).

Transfer learning.

## Kinematics of Circumgalactic Gas – Crystal Martin

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A few links related to the lecture coverage:

The green valley is a red herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early- and late-type galaxies (Schawinski et al, 2014).

The Large, Oxygen-Rich Halos of Star-Forming Galaxies Are A Major Reservoir of Galactic Metals (Tumlinson et al, 2011).

Gas in galactic halos (Dettmar, 2012).

Gaseous Galaxy Halos (Putman, Peek & Joung, 2012).

The kinematic connection between QSO-absorbing gas and galaxies at intermediate redshift (Steidel et al. 2002).

W. M. Keck Observatory.

Sloan Digital Sky Survey.

Virial mass.

Kinematics of Circumgalactic Gas (the lecturer is a co-author of this presentation).

Kinematics of Circumgalactic Gas: Quasars Probing the Inner CGM of z=0.2 Galaxies (-ll-). Here’s the paper: Quasars Probing Galaxies. I. Signatures of Gas Accretion at Redshift z ≈ 0.2 (Ho, Martin, Kacprzak & Churchill, 2017).

MAGIICAT III. Interpreting Self-Similarity of the Circumgalactic Medium with Virial Mass using MgII Absorption (Nielsen et al, 2013).

Fiducial marker.

Gas kinematics, morphology and angular momentum in the FIRE simulations (El-Badry et al, 2018).

## Black Hole Magnetospheres

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The lecturer says ‘ah’ and ‘ehm’ a lot, especially in the beginning (it gets much better later in the talk), but this is not a good reason for not watching the lecture. The last five minutes of the lecture after the wrap-up can safely be skipped without missing out on anything.

I’ve added some links related to the coverage below.

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Astrophysical jet.

Magnetosphere.

The Optical Variability of the Quasar 3C 279: The Signature of a Decelerating Jet? (Böttcher & Principe, 2009).

The slope of the black-hole mass versus velocity dispersion correlation (Tremaine et al., 2002).

Radio-Loudness of Active Galactic Nuclei: Observational Facts and Theoretical Implications (Sikora, Stawarz & Lasota, 2007).

Jet Launching Structure Resolved Near the Supermassive Black Hole in M87 (Doeleman et al., 2012).

Event Horizon Telescope.

The effective acceleration of plasma outflow in the paraboloidal magnetic field (Beskin & Nokhrina, 2006).

Toroidal magnetic field.

Current sheet.

No-hair theorem.

Frame-dragging.

Alfvén velocity.

Lorentz factor.

Magnetic acceleration of ultrarelativistic jets in gamma-ray burst sources (Komissarov et al., 2009).

Asymptotic domination of cold relativistic MHD winds by kinetic energy flux (Begelman & Li, 1994).

Magnetic nozzle.

Mach cone.

Collimated beam.

Magnetohydrodynamic simulations of gamma-ray burst jets: Beyond the progenitor star (Tchekhovskoy, Narayan & McKinney, 2010).

## Supermassive BHs Mergers

This is the first post I’ve posted in a while; as mentioned earlier the blogging hiatus was due to internet connectivity issues secondary to me moving. Those issues should now have been solved and I hope to soon get back to blogging regularly.

…

…

Some links related to the lecture’s coverage:

Supermassive black hole.

Binary black hole. Final parsec problem.

LIGO (Laser Interferometer Gravitational-Wave Observatory). Laser Interferometer Space Antenna (LISA).

Dynamical friction.

Science with the space-based interferometer eLISA: Supermassive black hole binaries (Klein et al., 2016).

Off the Beaten Path: A New Approach to Realistically Model The Orbital Decay of Supermassive Black Holes in Galaxy Formation Simulations (Tremmel et al., 2015).

Dancing to ChaNGa: A Self-Consistent Prediction For Close SMBH Pair Formation Timescales Following Galaxy Mergers (Tremmel et al., 2017).

Growth and activity of black holes in galaxy mergers with varying mass ratios (Capelo et al., 2015).

Tidal heating. Tidal stripping.

Nuclear coups: dynamics of black holes in galaxy mergers (Wassenhove et al., 2013).

The birth of a supermassive black hole binary (Pfister et al., 2017).

Massive black holes and gravitational waves (I assume this is the lecturer’s own notes for a similar talk held at another point in time – there’s a lot of overlap between these notes and stuff covered in the lecture, so if you’re curious you could go have a look. As far as I could see all figures in the second half of the link, as well as a few of the earlier ones, are figures which were also included in this lecture).

## Nephrology Board Review

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Some links related to the lecture’s coverage:

Diabetic nephropathy.

Henoch–Schönlein purpura.

Leukocytoclastic Vasculitis.

Glomerulonephritis. Rapidly progressive glomerulonephritis.

Nephrosis.

Analgesic nephropathy.

Azotemia.

Allergic Interstitial Nephritis: Clinical Features and Pathogenesis.

Nonsteroidal anti-inflammatory drugs: effects on kidney function (Whelton & Hamilton, J Clin Pharmacol. 1991 Jul;31(7):588-98).

Goodpasture syndrome.

Creatinine. Limitations of serum creatinine as a marker of renal function.

Hyperkalemia.

U wave.

Nephrolithiasis. Calcium oxalate.

Calcium gluconate.

Bicarbonate.

Effect of various therapeutic approaches on plasma potassium and major regulating factors in terminal renal failure (Blumberg et al., 1988).

Effect of prolonged bicarbonate administration on plasma potassium in terminal renal failure (Blumberg et al., 1992).

Renal tubular acidosis.

Urine anion gap.

Metabolic acidosis.

Contrast-induced nephropathy.

Rhabdomyolysis.

Lipiduria. Urinary cast.

Membranous glomerulonephritis.

Postinfectious glomerulonephritis.

## Lyapunov Arguments in Optimization

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I’d say that if you’re interested in the intersection of mathematical optimization methods/-algorithms and dynamical systems analysis it’s probably a talk well worth watching. The lecture is reasonably high-level and covers a fairly satisfactory amount of ground in a relatively short amount of time, and it is not particularly hard to follow if you have at least some passing familiarity with the fields involved (dynamical systems analysis, statistics, mathematical optimization, computer science/machine learning).

…

Some links:

Dynamical system.

Euler–Lagrange equation.

Continuous optimization problem.

Gradient descent algorithm.

Lyapunov stability.

Condition number.

Fast (/accelerated-) gradient descent methods.

The Mirror Descent Algorithm.

Cubic regularization of Newton method and its global performance (Nesterov & Polyak).

A Differential Equation for Modeling Nesterov’s Accelerated Gradient Method: Theory and Insights (Su, Boyd & Candès).

A Variational Perspective on Accelerated Methods in Optimization (Wibisono, Wilson & Jordan).

Breaking Locality Accelerates Block Gauss-Seidel (Tu, Venkataraman, Wilson, Gittens, Jordan & Recht).

A Lyapunov Analysis of Momentum Methods in Optimization (Wilson, Recht & Jordan).

Bregman divergence.

Estimate sequence methods.

Variance reduction techniques.

Stochastic gradient descent.

Langevin dynamics.

## An introduction to Invariant Theory

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I was strongly considering not watching this one to the end (…such as it is – the video cuts off before the talk was completely finished, but I’m okay with missing out on the last 2 (?) minutes anyway) at several points during the lecture, mainly because this is definitely far from a ‘gentle’ introduction; this one is tough for an introductory lecture and I had to look up a lot of stuff to just sort-of-kind-of muddle along. One of the things that I recall kept me from giving the rest of the lecture a miss along the way was that some parts of the coverage made me review a few topics in group theory which I’d previously encountered, but did not remember at all well – basically I was reminded along the way that concepts X, Y, and Z existed, and that I’d forgot how they worked/what they were useful for.

I think most (…non-mathematicians? …people?) who watch this one will miss a lot of stuff and details, and although you by watching it might get some idea what this stuff’s about I’m quite sure I’d not recommend this lecture to non-mathematicians; I don’t think it’s really worth it to watch it.

I’ve posted some links below to things related to the lecture’s coverage.

…

Invariant (mathematics).

Loop invariant.

Knot invariant.

Jones polynomial.

Homogeneous polynomial.

Invariant polynomial.

Invariant of a binary form.

Paul Gordan.

Polynomial ring.

Indeterminate (variable).

Ideal (ring theory).

Hilbert’s basis theorem.

Hilbert’s Nullstellensatz.

Group representation.

Group action.

Subalgebra.

Permutation matrix.

Symmetric polynomial.

Hilbert’s finiteness theorem.

Irreducible representation.

Multiplicative group.

One-parameter group.

Hilbert–Mumford criterion.

Strictly Upper Triangular Matrix.

Nilpotent matrix.

Characteristic polynomial.

## Mathematics in Cryptography III

As she puts it herself, most of this lecture [~first 47 minutes or so] was basically “an explanation by a non-expert on how the internet uses public key” (-cryptography). The last 20 minutes cover, again in her own words, “more theoretical aspects”.

Some links:

ARPANET.

NSFNET.

Hypertext Transfer Protocol (HTTP). HTTPS.

Project Athena. Kerberos (protocol).

Pretty Good Privacy (PGP).

Secure Sockets Layer (SSL)/Transport Layer Security (TLS).

IPsec.

Wireshark.

Cipher suite.

Elliptic Curve Digital Signature Algorithm (ECDSA).

Request for Comments (RFC).

Elliptic-curve Diffie–Hellman (ECDH).

The SSL/TLS Handshake: an Overview.

Advanced Encryption Standard.

Galois/Counter Mode.

XOR gate.

Hexadecimal.

IP Header.

Time to live (TTL).

Transmission Control Protocol. TCP segment structure.

TLS record.

Security level.

Birthday problem. Birthday attack.

Handbook of Applied Cryptography (Alfred J. Menezes, Paul C. van Oorschot and Scott A. Vanstone). (§3.6 in particular is mentioned/referenced as this is stuff she talks about in the last ‘theoretical’ part of the lecture).

## Mathematics in Cryptography II

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Some links to stuff covered in the lecture:

Public-key cryptography.

New Directions in Cryptography (Diffie & Hellman, 1976).

The history of Non-Secret Encryption (James Ellis).

Note on “Non-Secret Encryption” – Cliff Cocks (1973).

RSA (cryptosystem).

Discrete Logarithm Problem.

Diffie–Hellman key exchange.

AES (Advanced Encryption Standard).

Triple DES.

Trusted third party (TTP).

Key management.

Man-in-the-middle attack.

Digital signature.

Public key certificate.

Secret sharing.

Hash function. Cryptographic hash function.

Secure Hash Algorithm 2 (SHA-2).

Non-repudiation (digital security).

L-notation. L (complexity).

ElGamal signature scheme.

Digital Signature Algorithm (DSA).

Schnorr signature.

Identity-based cryptography.

Identity-Based Cryptosystems and Signature Schemes (Adi Shamir, 1984).

Algorithms for Quantum Computation: Discrete Logarithms and Factoring (Peter Shor, 1994).

Quantum resistant cryptography.

Elliptic curve. Elliptic-curve cryptography.

Projective space.

I have included very few links relating to the topics covered in the last part of the lecture. This was deliberate and not just a result of the type of coverage included in that part of the lecture. In my opinion non-mathematicians should probably skip the last 25 minutes or so as they’re – not only due to technical issues (the lecturer is writing stuff on the blackboard and for several minutes you’re unable to see what she’s writing, which is …unfortunate), but those certainly were not helping – not really worth the effort. The first hour of the lecture is great, the last 25 minutes are, well, less great, in my opinion. You should however not miss the first part of the coverage of ECC-related stuff (in particular the coverage ~55-58 minutes in), if you’re interested in making sense of how ECC works; I certainly found that part of the coverage very helpful.

## Computers, People and the Real World

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“An exploration of some spectacular failures of modern day computer-aided systems, which fail to take into account the real-world […] Almost nobody wants an IT system. What they want is a better way of doing something, whether that is buying and selling shares on the Stock Exchange, flying an airliner or running a hospital. So the system they want will usually involve changes to the way people work, and interactions with physical objects and the environment. Drawing on examples including the new programme for IT in the NHS, this lecture explores what can go wrong when business change is mistakenly viewed as an IT project.” (Quote from the video description on youtube).

Some links related to the lecture coverage:

Computer-aided dispatch.

London Ambulance Service – computerization.

Report of the Inquiry Into The London Ambulance Service (February 1993).

Sociotechnical system.

Tay (bot).

A few observations/quotes from the lecture (-notes):

“*The bidder who least understands the complexity of a requirement is likely to put in the lowest bid.*”

“It is a mistake to use a computer system to impose new work processes on under-trained or reluctant staff. – **Front line staff are often best placed to judge what is practical.**” [A quote from later in the lecture [~36 mins] is even more explicit: “The experts in any work process are usually the people who have been carrying it out.”]

“It is important to understand that in any system implementation the people factor is as important, and arguably more important, than the technical infrastructure.” (*This last one is a full quote from the report linked above; the lecture includes a shortened version – US*) [Quotes and observations above from ~16 minute mark unless otherwise noted]

“There is no such thing as an IT project”

“(almost) every significant “IT Project” is actually a business change project that is enabled and supported by one or more IT systems. Business processes are expensive to change. The business changes take at least as long and cost as much as the new IT system, and need at least as much planning and management” [~29 mins]

“Software packages are packaged business processes

*Changing a package to fit the way you want to work can cost more than writing new software” [~31-32 mins]

“Most computer systems interact with people: the *sociotechnical* view is that the people and the IT are two components of a larger system. Designing that larger system is the real task.” [~36 mins]