The v1.3.1 comparator used a sum-of-weights priorityScore. With weights
15..1 across 15 specs, three lower-priority specs (BNK+BRM+CRF, sum 39)
could outrank a single top-priority spec (HCR alone, sum 15). In
priority-order mode this surfaced lower-priority plans above the user's
top spec — the opposite of intent.
Fix: replace sum-of-weights with a lexicographic rank weight. Each spec
encodes as a bit, top-ranked spec = highest bit. So [HCR] = 16384 beats
[BNK,BRM,CRF,EMT,ENT,FIN,FIM,GLB,LCM,MGT,MKT,MTO,SBI,STR] = 16383. A plan
containing a higher-ranked spec ALWAYS outranks any plan that doesn't,
regardless of how many lower-ranked specs the latter contains. Lower
specs only act as tiebreakers among plans that all contain the same
higher-ranked spec.
Both modes use lex weight as the priority key; modes still differ in
ordering:
priority-order: (rankWeight desc, count desc, key asc)
maximize-count: (count desc, rankWeight desc, key asc)
Score display changes from the legacy sum (e.g. "score 29") to the lex
weight in compact form (e.g. "score 24.6k"). Hover for full integer.
The display now actually corresponds to ranking order.
Other:
- Cache cap (500k leaves) now retains existing entries instead of
clearing on overflow. New entries past the cap are dropped; the
cached subset stays available as a warm starting point.
- Two new lex-weight tests in searchDecisionTree.test.ts:
- single top-ranked spec outweighs all 14 others combined
- tiebreaker is the next-ranked spec
- All 84 tests pass; cached leaves stay valid across the comparator
change since achievedSpecs (the input to lex compare) is unchanged.
Files: solver/priority.ts (new functions), solver/decisionTree.ts
(comparators take ranking), components/{TopPlans,CourseSelection}.tsx
(score display + Recommended badge), state/appState.ts (cache-cap
behavior), vite.config.ts, CHANGELOG.md.
EMBA Specialization Solver
A client-side web application that helps EMBA students optimize their elective course selections to maximize the number of specializations they can earn.
The Problem
The J27 EMBA program offers 46 elective courses across 12 elective sets (Spring, Summer, Fall terms). Students select one course per set — 12 electives total, 30 credits. The program defines 14 specializations, each requiring 9+ credits (at least 4 qualifying courses). The catch: course credits do not duplicate across specializations. When a course qualifies for multiple specializations, its 2.5 credits must be allocated (potentially split) among them. This makes course selection a non-trivial credit allocation optimization problem.
Key constraints:
- Credit sharing: Each course's 2.5 credits are split across qualifying specializations — no double-counting
- Maximum 3 specializations: 12 courses × 2.5 credits = 30 total, and 3 × 9 = 27, so 3 is the theoretical max
- Required courses: 4 specializations require a specific course to be selected
- Strategy S1/S2 tiers: The Strategy specialization limits S2-marked courses to at most 1 contributing
Features
- Two optimization modes:
- Maximize Count — finds the largest set of achievable specializations, using ranking as a tiebreaker
- Priority Order — processes specializations in your ranked order, greedily adding each if feasible
- Drag-and-drop ranking — reorder specializations by priority
- Live optimization — results update instantly as you select courses
- Decision tree analysis — a Web Worker enumerates remaining course combinations to show ceiling outcomes per choice (how many specializations each option can lead to)
- Status tracking — each specialization is classified as achieved, achievable, missing a required course, or unreachable
- Mode comparison — shows what the alternative mode would produce so you can pick the better result
- Responsive — mobile layout with floating status banners
- State persistence — selections and rankings saved to localStorage
Tech Stack
- React 19 + TypeScript
- Vite 7 (dev server, bundler)
- javascript-lp-solver — linear programming for credit allocation feasibility checks
- @dnd-kit — drag-and-drop for specialization ranking
- Vitest — test runner
- Nginx — production static file server (Docker)
Prerequisites
- Node.js >= 22
- npm
- Docker and Docker Compose (for containerized deployment)
Development
All commands run from the app/ directory:
cd app
Install dependencies
npm install
Start the dev server
npm run dev
The app will be available at http://localhost:5173 with hot module replacement.
Run tests
npm test
Or in watch mode:
npm run test:watch
Lint
npm run lint
Build for production
npm run build
Output goes to app/dist/.
Preview production build locally
npm run preview
Deployment
Docker Compose (recommended)
From the project root:
docker compose up -d
This builds a multi-stage Docker image:
- Build stage — installs dependencies and runs
vite buildin a Node 22 Alpine container - Serve stage — copies the built static files into an Nginx Alpine container
The app is served on port 8080 by default. Override with the PORT environment variable:
PORT=3000 docker compose up -d
Docker (standalone)
docker build -t emba-solver .
docker run -p 8080:80 emba-solver
Static hosting
Run npm run build in app/ and deploy the app/dist/ directory to any static file host (Netlify, Vercel, S3, GitHub Pages, etc.). The app is fully client-side with no backend dependencies.
Project Structure
├── Dockerfile # Multi-stage build (Node → Nginx)
├── docker-compose.yml # Single-service compose config
├── nginx.conf # Nginx config with gzip, caching, SPA fallback
└── app/ # Vite + React application
├── src/
│ ├── main.tsx # Entry point
│ ├── App.tsx # Root component
│ ├── data/ # Static course/specialization data
│ │ ├── types.ts # TypeScript interfaces
│ │ ├── courses.ts # 46 courses with qualifications
│ │ ├── electiveSets.ts # 12 elective sets
│ │ ├── specializations.ts # 14 specializations
│ │ └── lookups.ts # Derived indexes
│ ├── solver/ # Optimization engine
│ │ ├── optimizer.ts # Maximize-count & priority-order modes
│ │ ├── feasibility.ts # LP-based feasibility checks
│ │ └── decisionTree.ts # Exhaustive ceiling analysis
│ ├── components/ # UI components
│ ├── state/ # App state (useReducer + localStorage)
│ ├── hooks/ # Custom hooks (useMediaQuery)
│ └── workers/ # Web Worker for decision tree
└── vite.config.ts
How the Solver Works
- Feasibility checking — uses a linear program (LP) to determine whether a target set of specializations can each reach 9 credits given the selected courses, respecting per-course capacity (2.5 max) and the Strategy S2 constraint
- Maximize Count — tries all combinations of candidate specializations from size 3 down to 1, checking LP feasibility for each; among equal-size feasible sets, picks the one with the highest priority score based on ranking
- Priority Order — iterates specializations in rank order, greedily adding each to the achieved set if the combined set remains LP-feasible
- Decision tree — for each open (unselected) elective set, enumerates all possible remaining course combinations to compute the best-case outcome per choice, helping users identify which selections matter most