1% ============================================================================2% Part II — The Evolution of Computer Science3% Written by Agent L (Academic Writer), WP44, 2026-11-03.4% Bibliography: references_part02.bib (every key verified; see references_verification_part02.csv).5% Corpus quantities only through the macros of tables/numbers.tex; \pending{} marks missing macros.6% ============================================================================78\section{The disciplinary structure of computer science}9\label{sec:p2-structure}1011Any claim that computer science has been transformed since late 2022 presupposes a map of the discipline on which the transformation can be located. That map is not given by nature. Computer science is organised simultaneously by its objects (processors, programs, data, networks, users), by its methods (proof, construction, measurement, learning), and by the communities and venues through which results circulate; the three organisations overlap only partially, and every bibliometric classification is a compromise among them. This section describes the compromise adopted in the present study and the alternatives against which it must be read. It serves two purposes for the remainder of the manuscript: it fixes the vocabulary of \emph{areas} and \emph{categories} used in Parts~V--IX, and it makes explicit the sense in which a ``shift of research toward artificial intelligence'' is a measurable proposition rather than a slogan.1213\subsection{Classification schemes and what they encode}14\label{sec:p2-schemes}1516Four classification systems are relevant to a corpus of the kind assembled here, and they encode the structure of the discipline in different ways.1718The \emph{ACM Computing Classification System} (CCS) is the only one produced by a professional society as an explicit ontology. Its 2012 revision replaced the 1998 four-level scheme with a poly-hierarchy of roughly two thousand concepts organised under thirteen top-level nodes, among them ``Theory of computation'', ``Computing methodologies'' (which houses artificial intelligence, machine learning, computer graphics and simulation side by side), ``Computer systems organization'', ``Software and its engineering'', ``Security and privacy'', ``Human-centered computing'' and ``Networks'' \citep{rous2012ccs}. The CCS is a statement of how the ACM understood the field in 2012. It is applied by authors at submission time, is used almost exclusively in ACM venues, and is therefore sparse in any corpus that spans IEEE, Springer, Elsevier, open-access publishers and preprint servers. Its value for this study is conceptual rather than operational: it provides an independent, expert-designed reference against which the forty categories of CLAUDE.md~\S4 can be positioned, and it documents a pre-transformer view in which large language models, foundation models, AI agents and AI safety do not exist as concepts at all.1920The \emph{arXiv subject classes} are the second system. arXiv was created in 1991 for high-energy physics and its taxonomy reflects that origin; the computer science archive (\texttt{cs}) is organised into forty subject classes largely inherited from the ACM scheme of the 1990s \citep{ginsparg2011arxiv}. Authors choose a primary class and may add cross-lists, so the classification is self-reported, multi-label, and coarse. Its distinctive property is temporal: a preprint is classified at the moment of submission, before peer review, so the arXiv class records how authors positioned their work at the time, not how a later indexer reconstructed it. For the questions of this paper that property matters: when a paper on, say, program verification with language models is submitted to \texttt{cs.PL} with a cross-list to \texttt{cs.LG}, the pair of classes is a small but genuine piece of evidence about disciplinary boundaries as practitioners perceive them.2122The \emph{DBLP computer science bibliography} is the third. DBLP does not classify papers at all; it classifies \emph{venues}. Begun in 1993 as a database and logic programming bibliography and extended to the whole of computer science, it records the tables of contents of conferences and journals with curated author identities \citep{ley2002dblp}. Membership in DBLP is itself a judgement that a venue belongs to computer science, and the venue stream to which a paper belongs is a strong signal of community: a paper in the proceedings of OSDI is an operating-systems paper in the sociological sense whatever its subject matter. DBLP therefore encodes the discipline as a set of communities rather than as a set of topics, and the two encodings disagree precisely where this paper expects change, namely where machine-learning methods enter venues that were not built for them.2324The fourth system is the family of \emph{algorithmic, citation-based classifications} that underlie modern open bibliographic indexes. OpenAlex, which succeeded the Microsoft Academic Graph after the latter was discontinued at the end of 2021 \citep{wang2020mag,priem2022openalex}, assigns to every work a ranked list of \emph{topics} from a fixed vocabulary of about 4{,}500 topics grouped into subfields, fields and domains; the topics were obtained by clustering the citation network and labelling the clusters with a language model, and are assigned to new works by a classifier over title, abstract and venue \citep{openalex2025topics}. The approach descends from the publication-level clustering methodology of \citet{waltman2012classification}, refined by the Leiden community-detection algorithm \citep{traag2019leiden}, and it inherits the known properties of that family: clusters are well connected and reproducible, but their granularity is a free parameter with no natural value \citep{sjogarde2018granularity}, and citation-based taxonomies, while more accurate than text-based or journal-based ones on average \citep{klavans2017taxonomy}, lag behind the literature by construction because a cluster must accumulate citations before it can exist. The Semantic Scholar academic graph offers a comparable but differently constructed resource \citep{kinney2023s2}. Older, journal-based classifications of the kind proposed by \citet{glanzel2003classification} remain in use in evaluative scientometrics but are too coarse, and too journal-centric, for a conference-dominated discipline.2526Each of these systems is a model of the discipline with its own inductive bias. The CCS encodes expert judgement frozen in 2012; arXiv classes encode author self-positioning at submission; DBLP streams encode venue communities; OpenAlex topics encode citation neighbourhoods as of a recent snapshot. None of them is ground truth, and this study treats their disagreements as data rather than as noise.2728\subsection{The forty-category ontology of this study}29\label{sec:p2-ontology}3031The classification used throughout the manuscript is the hierarchical ontology specified in CLAUDE.md~\S4 and built in Phase~2 (Appendix~A). It comprises forty leaf categories grouped into eight areas: artificial intelligence and machine learning (nine leaves, from large language models to AI safety); perception, language, robotics and interaction (six); software, programming languages and formal methods (four); theory of computation (two); data, information and distributed systems (six); security, privacy and trust (five); hardware, architecture and emerging computing (five); and computational science and discovery (three). A small number of \emph{specialisation} edges record that one leaf refines another: large language models and multimodal AI refine foundation models; compilers refine programming languages; cloud and edge computing refine distributed computing; federated learning refines privacy-preserving computation; AI accelerators refine computer architecture. The areas are a reporting device; classification operates on leaves.3233The assignment rule is deliberately simple so that it can be audited. Let $\mathcal{W}$ be the set of works and $\mathcal{C}$ the set of forty leaves. For each leaf $c$ the ontology lists weighted signals of five types $k \in \{\text{topic},\ \text{subfield},\ \text{arXiv},\ \text{stream},\ \text{keyword}\}$, with signal set $S_k(c)$ and weights $\omega_{kj} \in (0,1]$ for $j \in S_k(c)$. A work $w$ matches a signal $j$ if the corresponding attribute of $w$ (an OpenAlex topic identifier, a subfield, an arXiv class, a DBLP stream, or a regular expression over title and abstract) contains it. The score of $w$ for $c$ is34\begin{equation}35s(w,c) \;=\; \sum_{k} \min\Bigl\{1,\ \sum_{j \in S_k(c)} \omega_{kj}\, \mathbf{1}[w \text{ matches } j]\Bigr\} \;-\; \infty \cdot \mathbf{1}[w \text{ matches an exclusion of } c],36\label{eq:p2-score}37\end{equation}38so that no single signal type can contribute more than one unit, a weight of one means ``this signal alone suffices'', and an exclusion pattern vetoes the leaf outright. The work belongs to every leaf with $s(w,c) \geq 1$; its \emph{primary} leaf is $\arg\max_c s(w,c)$, with ties broken in favour of a child over its parent and then by category number. Multi-label membership is not an accident of the rule but its purpose: an instruction-tuning paper is expected to score in both large language models and natural language processing, and the share of works with more than one leaf is itself one of the quantities tracked in Part~IX.3940Two design choices deserve comment because they shape every downstream result. First, the ontology is not a relabelling of OpenAlex topics. Six AI categories that the citation-based topics cannot separate (large language models, foundation models, multimodal AI, generative AI, AI agents, AI safety) and seven small categories with no dedicated topic or venue (federated learning, sustainable computing, autonomous scientific discovery, privacy-preserving computation, blockchain, quantum computing, edge computing) rely on keyword patterns of weight one; the build fails if such a pattern is absent. The reason is historical and is the subject of Section~\ref{sec:p2-waves}: the citation clusters that OpenAlex labels were formed by a literature in which ``large language model'' was not yet a stable term, and a topic such as ``Topic Modeling'' in fact hosts most BERT-era and retrieval-augmented work. Second, the ontology is positioned relative to the CCS rather than derived from it. The AI area corresponds to the CCS branch \emph{Computing methodologies $\to$ Artificial intelligence / Machine learning}, but the leaves inside it are drawn from the post-2017 literature; theory, systems, networks, security and human-centred computing map onto the corresponding CCS top-level nodes almost one-to-one; computational biology, scientific computing and sustainable computing sit in CCS under \emph{Applied computing} and \emph{Social and professional topics}, which the present ontology promotes to first-class areas because the questions of this paper concern precisely the traffic between computing and the sciences it serves.4142The ontology's limitations are stated in Appendix~A and are not repeated here, except for one that bears on interpretation. A category defined partly by keywords is defined partly by vocabulary, and vocabulary changes faster than research practice. If the phrase ``large language model'' spreads into papers whose methods are unchanged, a keyword-driven category will register growth that is partly nominal. Section~\ref{sec:p2-claims} returns to this problem under the heading of LLM-assisted writing; Part~IV describes the embedding-based checks designed to detect it.4344\subsection{Where the classifications disagree}45\label{sec:p2-disagree}4647The disagreements among the four systems are systematic, and they fall into three kinds.4849The first is \emph{coverage}. Comparisons of bibliographic databases consistently show that no source indexes the whole of a discipline and that the gaps are not random: conference proceedings, preprints, and non-English venues are the most unevenly covered \citep{visser2021comparison,martinmartin2021coverage}. OpenAlex, the backbone of this corpus, inherits the broad but uneven coverage of Microsoft Academic and Crossref; its reference lists are less complete than those of the commercial indexes for part of the period, which affects citation-based measures more than counts \citep{culbert2025openalex}. The linking phase of this study illustrates the scale of the problem at the level of record identity. The OpenAlex snapshot contains \LinkOaCsRecords{} works classified in computer science between 2018 and 2026; DBLP contributes \LinkDblpTwoZeroOneEightTwoZeroTwoSix{} records over the same years, of which \LinkDblpLinkedDistinct{} could be matched to an OpenAlex work by DOI or by title and year in the first linking pass and \LinkDblpUnlinked{} could not; the arXiv \texttt{cs} harvest contributes \LinkArxivCsRecords{} preprints, of which \LinkArxivLinkedDistinct{} were matched, overwhelmingly through the arXiv identifier that OpenAlex stores. These are linkage statistics, not findings about research, but they establish that a classification applied to one source cannot simply be transferred to another: a non-trivial fraction of the venue-defined (DBLP) universe has no citation-defined (OpenAlex) counterpart, and vice versa. Part~III describes the second linking pass and the treatment of unmatched records.5051The second kind of disagreement is \emph{granularity and boundary}. The arXiv class \texttt{cs.LG} is one node among forty; in OpenAlex, machine learning spreads across dozens of topics in several fields, including statistics, engineering and medicine, because the citation network does not respect the boundary of the computer-science field. Conversely, OpenAlex's field~17 (``Computer Science'') contains clusters on educational technology, media studies and physics that no computer scientist would claim, and the ontology of this study deliberately leaves most of them unmapped (Appendix~A). The practical consequence is that the apparent size of ``AI'' depends on which boundary is used: a venue-based definition (DBLP streams of NeurIPS, ICML, ICLR, AAAI and the vision and language conferences) gives a different set from a topic-based definition, which gives a different set again from an arXiv-class definition, and the three sets diverge most in the applied sciences, where machine-learning methods are used without the paper belonging to any machine-learning community. The multi-label design of the ontology, and the use of all three signal types with capped weights in equation~\eqref{eq:p2-score}, is the response to this divergence: a work that is an AI paper by every criterion scores high on all of them, while a work that is an AI paper by vocabulary alone is held to a higher evidentiary standard.5253The third kind is \emph{temporal}. The CCS was fixed in 2012 and the arXiv classes are older still; OpenAlex topics were generated from a citation network observed in the early 2020s and are reassigned when the snapshot is rebuilt; DBLP streams are stable but new venues appear and old ones are renamed. A classification that does not change cannot register the emergence of a field except as the growth of an existing node; a classification that is regenerated cannot be compared across snapshots without care. Neither property is a defect, but they pull in opposite directions, and a study of structural change must choose. This study freezes all classifications at a single snapshot (Part~III), so that any growth it reports is growth of a fixed category, and it treats the emergence of \emph{new} categories as a separate detection problem (Part~IV, Section~\ref{sec:p2-claims}).5455A final, sociological disagreement should be named explicitly because it affects what counts as a ``paper''. Computer science is unusual among the sciences in treating selective conferences as the primary venue of record, a practice that has been defended on grounds of speed and criticised on grounds of reviewing quality and the fragmentation of the literature \citep{vardi2009conferences,fortnow2009growup}. The convention has two consequences for bibliometrics. Conference papers are indexed less uniformly than journal articles, so coverage disagreements are concentrated in exactly the venues that the discipline values most; and the conference calendar imposes a strong seasonality on publication dates, so that monthly series must be deseasonalised before any break can be read off them. The preprint culture adds a third consequence. Computer scientists came to arXiv late relative to physicists and mathematicians, and a large share of computer-science preprints are never matched to a published version, either because they are not published or because the match fails \citep{lin2020preprints}. A corpus that counts preprints and published versions as separate works will over-count the preprint-heavy subfields; a corpus that links them will under-count whenever linkage fails; and the subfields where linkage fails most often are, again, the fast-moving ones.5657\subsection{Why the growth of a field is hard to measure}58\label{sec:p2-growth}5960The questions of this paper are ultimately about rates: of publication, of citation, of movement between categories. Rates presuppose denominators, and the denominators of science are themselves contested quantities.6162The literature on the growth of science offers two sobering lessons. The first is that measured growth depends heavily on the database. Using cited references as a proxy for the literature that scientists actually use, \citet{bornmann2015growth} estimated the long-run growth of science at roughly three per cent per year with a doubling time of about a quarter of a century, while estimates based on the publication counts of individual databases vary widely with the database's coverage policy and its own expansion. A later analysis with segmented growth curves across several databases found that the growth rate has itself changed over time, with faster growth in recent decades, but that the location of the segments depends on the source \citep{bornmann2021growth}. For the present study the lesson is that a change in the volume of computer-science publications between 2018 and 2026 is the sum of a change in research activity and a change in indexing, and that only the first is of scientific interest. OpenAlex grew substantially during the period as it absorbed new sources and improved its matching; the indexing lag (the delay between a work's publication and its appearance in the snapshot) is longest for the most recent months, so that any series ending in 2026 slopes downward at its end for reasons that have nothing to do with research. These are among the pre-period diagnostics and sensitivity checks required by CLAUDE.md~\S6.5 and specified in Part~IV.6364The second lesson concerns the ``science of science'' as a field in its own right. The programme described by \citet{fortunato2018sos} and developed at book length by \citet{wang2021sos} has established robust regularities: citation distributions are heavy-tailed within every field; team size has grown steadily; novelty in the sense of atypical combinations of prior work is associated with higher impact at the top of the distribution; and the productivity of individual scientists is approximately stable over careers. Those regularities are the background against which any field-specific claim must be read. A rise in the citation inequality of AI papers after 2022, for instance, is interesting only if it exceeds the inequality that heavy-tailed citation distributions produce in every growing field; the hypotheses H1--H8 of the preregistered protocol (Part~III) are formulated as comparisons between the post-2022 period and the baseline for that reason.6566A further difficulty is specific to computer science and concerns what the discipline takes itself to be. \citet{denning2005science} argued that computer science is a science of information processes and not merely an engineering of artefacts, and \citet{wing2006computational} that ``computational thinking'' is a general intellectual skill rather than a professional one; both arguments were written at a moment when the discipline was defending its boundaries. The post-2022 period raises the converse question: whether the discipline's methods have diffused so widely that the boundary is no longer where the classifications place it. Papers that apply learned models to protein structure, materials, weather or law are classified as computer science by some systems and not others; a transformation that consists partly of such diffusion is partly invisible to a classification that keeps the boundary fixed. The ontology's eighth area, computational science and discovery, and the ``penumbra'' set defined in Part~III (works with a computer-science topic but without venue or arXiv support) exist to make that diffusion observable without inflating the core.6768\section{Three prior transformations and how they propagated}69\label{sec:p2-waves}7071The post-2022 period is not the first time computer science has been reorganised around a new technology. Three earlier transformations are directly relevant because they established the publication practices, the infrastructure, and the conceptual vocabulary within which the present one unfolds: the internet and web era, which created the systems and the industrial research laboratories; the deep-learning wave of 2012--2017, which created the benchmark culture and the compute economy; and the transformer and pretraining era of 2017--2022, which created the models themselves. For each, the account below is deliberately narrow. It does not attempt a history of computing; it asks what changed in how research was done and published, and how the change propagated from the subfield in which it began to the others. The answers suggest a way of reading the post-2022 data that the empirical parts of this paper then test.7273