Combinatorics
Counting, arrangement and structure of discrete sets: enumeration, graph theory, design theory.
Founded: 1900 — No single founding event — ancient roots (Pascal's triangle, Euler's Königsberg bridges); became a systematically organized field with Fisher's design theory in the 1920s (approximate)
The claim
No credible dismissal found. Retrospectives repeat only a vague, unattributed folk memory that combinatorics was “unserious” mid-century, with no named person or exact quote. One narrow, dated anecdote: Mittag-Leffler shelved 18th-century “combinatorial school” texts under a library label “Dekadenter” (decadent) — targets one obsolete pre-1900 formalist tradition, not the modern field.
What happened
no meaningful gap — organized and applied at roughly the same time
Verdict: Never dismissed, applied anyway.
Confidence: medium.