WG211/M25Schedule

IFIP Working Group 2.11, Twenty-fifth Meeting

Group Picture

December 2-5, 2025, Stellenbosch, South Africa

The meeting will be held in Stellenbosch, South Africa, hosted by Bernd Fischer. The meeting is planned for 3.5 days, with a half day on December 5. More details, program, and registration information will be appearing on this page in the next few weeks.

Venue

The meeting will be held at the Wallenberg Center of the Stellenbosch Institute for Advanced Study (Streetview). This is to the east of the Stellenbosch University Campus (Campus map). Most B&B's, hotels, and restaurants are within 10-15mins walk.

We need to follow the venue's standard schedule (start at 9:00, out by 17:30 sharp), 90min sessions, 30mins tea breaks, lunch 12:30 - 14:00.

STIAS' doors open at 8:00, and there's some coffee but no breakfast; that should be covered by your B&B. I think it is good enough to arrive by 8:45, give or take a few minutes.

Group dinners

Stellenbosch has many restaurants, but they get quite busy from mid-November. I have thus made dinner reservations for 19:00 each night:

• Tuesday: De Vier
• Wednesday: Spek en Bone
• Thursday: De Vleispaleis

For people attending the excursion, I have made a reservation at 19:30:

• Friday: De Eetkamer

All restaurants are within walking distance from the old town. All restaurants have vegetarian options available, despite their names ;-).

Group excursion

I have arranged a group excursion on Friday, Dec 5. We will be visiting Boulder's Beach for penguin watching and take the cable car up to Table Mountain, with time for a walk at the plateau. We will be doing a wine tasting along the way - this is the winelands, after all!

Note that Table Mountain has a notoriously fickle weather, and could be shrouded in clouds (the so called "table cloth") any time. If the weather doesn't co-operate, we will drive to Cape of Good Hope as a backup.

Departure will likely be around 8:30 or 9:00, return to Stellenbosch should be around 18:00 or 18:30, depending on traffic.

Please sign up here if you plan to attend.

• Michael Adams
• Shraddha Barke
• Jacques Carette (+1)
• Sebastian Erdweg (have to leave before dinner)
• Bernd Fischer
• Cezary Kaliszyk
• Ohad Kammar
• Yuito Murase
• Klaus Ostermann
• Moeketsi Raselimo
• Chung-Chieh Shan
• Friedrich Steimann (have to leave with Sebastian)
• Michel Steuwer
• Eric Van Wyk
• Jeremy Yallop
• Julia Lawall

Registration fee

Registration fee for the meeting is EUR 275 / ZAR 5500; this covers all lunches on the meeting days and the dinners Tuesday - Thursday (including reasonable amounts of drinks ;-). Additional dinner tickets for partners will be EUR 150 / ZAR 3000.

The cost for the excursion on Dec 5 will be EUR 125 / ZAR 2500 (based on 16 people attending; the price will go up slightly if fewer people attend, because of the fixed bus hire costs); this includes transport, entrance fees at Boulder's Beach, the Table Mountain cable car, boxed lunch and wine tasting, and dinner at De Eetkamer in Stellenbosch.

Payment is in cash (either in Euros or in Rand) on arrival, or via electronic bank transfer; please mail me for the account details, if you want to use that option. I will issue a signed receipt on University stationary for the amount paid in the currency used.

Members attending

Please add your name to the following list (alphabetical by last name, please) if you are planning to attend the meeting.

• Jacques Carette
• Sebastian Erdweg
• Bernd Fischer
• Ohad Kammar
• Julia Lawall
• Klaus Ostermann
• Chung-chieh Shan
• Friedrich Steimann
• Eric Van Wyk
• Jeremy Yallop

Guests and Observers

• Michael Adams
• Shraddha Barke
• Loek Cleophas (local observer)
• Cezary Kaliszyk
• Yuito Murase (as proxy of Atsushi Igarashi)
• Moeketsi Raselimo (local observer)
• Michel Steuwer

Talks

The following people have confirmed they will giving a talk:

• Michael D. Adams
• Shraddha Barke Toward Trustworthy LLM Generation: From Verifiable Proofs to Reliable Agents
• Jacques Carette Definite Folds
• Sebastian Erdweg: Differential Execution with Lexical Tracing
• Bernd Fischer (or maybe Moeketsi Raselimo) Learning Lexical Structure of Black-Box Systems via Repeated String Edit Operations
• Cezary Kaliszyk
• Ohad Kammar Intrinsically typed and well-scoped SMTLIB FFI bindings with modular abstract syntax trees (MAST)
• Julia Lawall TBD
• Yuito Murase and Atsushi Igarashi Refined^2 Environment Classifiers
• Chung-chieh Shan Simulating Quantum Computation Using Probabilistic Programming (slides)
• Friedrich Steimann Relative Multiplication of Infinite Relations
• Michel Steuwer Slotted E-Graphs
• Jeremy Yallop Frex: Dependently Typed Algebraic Simplification
• Eric Van Wyk: On Scope Graphs and Reference Attribute Grammars: Answering Eelco's Questions

Schedule

Tuesday, December 2

• 08:45 - 09:00 Assemble and welcome
  • 09:00 - 09:45 Van Wyk
  • 09:45 - 10:30 Barke
• 10:30 - 11:00 Coffee break
  • 11:00 - 11:45 Erdweg
• 12:30 - 14:00 Lunch and break
  • 14:00 - 14:45 Adams
  • 14:45 - 15:30 Fischer / Raselimo
• 15:30 - 16:00 Coffee break
  • 16:00 - 16:45 Discussion

• 19:00 Dinner: De Vier

Wednesday, December 3

• • 09:00 - 09:45 Carette
  • 09:45 - 10:30 Steuwer
• 10:30 - 11:00 Coffee break
  • 11:00 - 11:45 Steimann
  • 11:45 - 12:30 Kammar
• 12:30 - 14:00 Lunch and break
  • 14:00 - 14:45 Kaliszyk
  • 14:45 - 15:30 Lawall
• 15:30 - 16:00 Coffee break
  • 16:00 - 16:45 TBD

• 18:30 Dinner: Spek en Bone

Thursday, December 4

• • 09:00 - 09:45 Yallop
  • 09:45 - 10:30 Murase
• 10:30 - 11:00 Coffee break
  • 11:00 - 11:45 Shan
  • 11:45 - 12:30 TBD
• 12:30 - 14:00 Lunch and break
  • 14:00 - 14:45 TBD
  • 14:45 - 15:30 TBD
• 15:30 - 16:00 Coffee break
  • 16:00 - 17:30 Business Meeting

• 19:00 Dinner: De Vleispaleis

Travel

Note that the meeting will be in the southern Summer, just before the local holiday season starts in earnest, and Stellenbosch (and all of South Africa) will be getting busy, so arrange your flights and accommodation early.

Visa Information

Visitors from most EU countries, US, Canada, Japan, Australia and most of South America don't need a visa to visit South Africa. The complete (official) list is available at the Department of Home Affairs. Please contact Bernd Fischer if you need a visa to visit South Africa; please note that applications can take substantial amounts of time to get processed (although the backlog has been cleaned up after the last election...)

Vaccinations and Prophylaxis

South Africa requires yellow fever vaccinations for travelers arriving from a risk area; this includes most of South America and Central Africa, but excludes Europe, North America, Asia, and Oceania. You should probably have up-to-date standard vaccinations (such as tetanus) as you would have for travel in Europe or North America. Malaria prophylaxis is only required if you go to Kruger National Park or Victoria Falls.

The medical system is very good around Stellenbosch, but sometimes less so in other parts of the country. Check with your (travel) insurance whether they cover your trip.

Getting to Stellenbosch

The closest airport to Stellenbosch is Cape Town International (CPT / FACT). There are direct flights from London (Virgin, BA), Amsterdam (KLM), Paris (Air France), Frankfurt (Condor, Lufthansa), Munich (Lufthansa), Zuerich (Edelweiss), Istanbul (Turkish Airlines), Doha (Qatar Airways), Dubai (Emirates), Addis Ababa (Ethiopian), Washington (United), Newark (United), Atlanta (Delta), and Singapore (Singapore Airlines). Note that some of these flights are seasonal and operate only during the southern Summer, so they might not show up yet. There are also regional connections to many places in southern Africa (e.g., Windhoek).

Further connections (e.g., from India, East Asia, Australia, or South America) are available with a transfer in Johannesburg. I recommend to fly into Cape Town, if feasible, because the transfer in Johannesburg requires you to clear immigration and customs (like in the US), which can be a bit unpredictable.

Flight prices vary of course wildly. I have recently paid anything between EUR 700 and 1200 for a Germany round trip, and EUR 1500 for a California round trip.

CPT is about 35km from Stellenbosch; there is no public transport, but Uber is widely available, cheap (< EUR 20 to Stellenbosch), and I always take it. Please be aware that taxi touts will try to talk you into a metered taxi as soon as you leave customs; I always politely ignore them.

If you prefer a pre-booked airport shuttle, try:

• Bettina's
• Shuttle Up

Stellenbosch is small and easily navigable by foot, and the venue is in walking distance to most hotels and B&Bs. You won't need a rental car unless you are planning to go on a road-trip before or after the conference. There is no public transport in Stellenbosch; do *not* take the train to Cape Town, or a minibus taxi.

Accommodation

Stellenbosch does not have big corporate hotels but offers a wide variety of different smaller accommodation options. Most centrally located B&Bs (look for the "Stellenbosch Central" or "Mostertsdrift" areas) will be in the range from EUR 80 to EUR 150 per night; there are also Airbnb-style accommodations but they tend to be more in the suburbs, and are not necessarily cheaper. Many wine farms offer luxury accommodation, but they are typically out of town and require a rental car.

Below are a number of guest houses covering different price ranges. Note that I haven't stayed in any of these... Please make your own arrangements and please note that places begin to fill up.

Between Stias and the town center:

• Avenues Guesthouse, 32 Die Laan
• Beauclair Guest Cottage, 1 Coetzenburg Road
• Bonne Esperance, corner of Neethling and Van Riebeeck
• Caledon Villa, 7 Neethling Street
• De Haas Luxury Living - Die Laan, 2 Die Laan
• De Haas Luxury Living - Die Laan 40, 40 Die Laan
• Evergreen Manor, 11 Murray Street
• Kolonie's Tuin, 22 Die Laan
• Laanhof, 28 Die Laan (self-catering)
• Life & Leisure, 20 Van Riebeeck St
• Middedorp Manor, 14 Neethling Street
• Minserie Collection, Minserie Street (self-catering)
• River Manor, 6-8 Die Laan
• Roosenwijn Guesthouse, 14 Van Riebeeck Street
• De Haas Luxury Living - Villa Grande, 1 Keeroom Street

Mostertsdrift (east of Stias):

• 5 Seasons Guesthouse, 60 Van Der Stel Street
• Lanzerac Wine Estate, Lanzerac Road (wine estate in walking distance from Stias)
• Stellenbosch Manor, 2 Van Der Stel Street
• Summerwood Guest House, 28 Jonkershoek Road
• Van Der Stel Manor, 64 Van Der Stel Street

Town center:

• Batavia Boutique Hotel, 12 Louw Street
• Coopmanhuijs Boutique Hotel & Spa, 33 Church Stree
• Eendracht Hotel & Self Catering, 160 Drop Street
• Just Joey Lodge, 13 Noordwal-Wes
• Stellenbosch Hotel, corner of Dorp & Andringa

Security

South Africa has a reputation as an unsafe country but most crimes happen in township areas, and the center of Stellenbosch is generally safe; walking around town, or from town to the guesthouses in Mostertsdrift is fine, even after dinner. However, there are a few things to keep in mind:

• Do not flash your valuables (phone, wallet, camera) in public.
• Do not hand over your ATM/credit card - servers will bring a machine to your table (or will ask you to pay at the counter); if you withdraw money from an ATM, check that nobody is lurking around, and do not accept "help" from people.
• Do not walk or drive into any township (in Stellenbosch, that means Kayamandi and Cloetesville); if you are interested, you can book guided tours.
• Do not take the train between Cape Town and Stellenbosch (or trains around Cape Town).

Weather

Early December is late spring in South Africa. The weather in Stellenbosch should be nice - the average day-time highs are around 25C, night-time lows around 15C, and it should be dry. However, there are chances of an early heat wave, with temperatures above 30C, or (fortunately less likely) a late rain front with temperatures dropping by 5-10 degrees.

Pre- / post-meeting excursions

Here are a few ideas if you are planning to spend a few extra days in Stellenbosch or travel around the country:

• Spend the weekend in Cape Town and explore the city - Table Mountain is certainly a prime target. You could also go to Kirstenbosch Botanical Garden (although the prime bloom will be over then), and even climb Table Mountain from there (although this could be hot and strenuous that time of the year). Cape Town has quite a lot of night life, especially on the weekend.
• Explore the Stellenbosch surroundings. For this, you should probably get a rental car. There are literally hundreds of wine farms in the surroundings, if you want to go for a tasting. The Paarl Taal Monument (monument to the Afrikaans language) is an interesting cultural experience, and you can go on to the Paarl rock (large granite Boulder). Franschhoeck is a another cute town.
• Get out to the Cederberg Mountains - a nice mountainous area about 2-3hours north of Cape Town, with nice mountain walks (Wolfberg Cracks, some caves). You could stay at Clanwilliam, or look for a place in the mountain reserve (look for Algeria). The roads are mostly dirt (ie unpaved) but we have driven them in a Polo...
• Hike the Bosmanskloof Traverse (either as an overnight hike, or as a day-hike), staying in McGregor or Grayton.
• Go to Calitzdorp for Port tasting, Oudtshoorn for the ostriches (and the very tourist-trappy Cango Caves, a huge limestone cave), and drive some of the old Mountain passes, like Swartbergpass into Prince Albert, a quaint Karoo town, and "poorts" (i.e., mountain notches), like Seweweekspoort.
• Go shark cage diving in Struisbaai.

Except for the Cape Town weekend, most trips will require a rental car. You can get an uber or a dedicated driver for a wine tasting tour, which is probably a smart idea in the first place...

Safaris. There are no lions running around in Stellenbosch ;-). The closest ones are at the Drakenstein Lion Park, which is basically a retirement home for lions. There are a few private game reserves within two to three hours drive of Stellenbosch (e.g., Garden Route Game Lodge or Sanbona), but they are not cheap. The closest National Parks with substantial wildlife are Mountain Zebra NP and Addo Elephant NP (about 8-10hrs drive from Stellenbosch, but Addo is quite close to Port Elizabeth, which is one hour by plane from Cape Town). If you plan to visit Krueger NP you should probably fly with a stop-over in Johannesburg, and plan on at least four extra days.

Arrivals and departures of attendants

• Friedrich will arrive on Monday morning (Condor flight DE2290, ETA 10:45 am) and leave on Friday evening (DE2291 at 7:50 pm); will stay at Evergreen Manor.
• Sebastian will arrive on Monday morning (Condor flight DE2290, ETA 10:45 am) and leave on Friday evening (DE2291 at 7:50 pm); will stay at Evergreen Manor.
• Julia will arrive on Monday morning at 5:50am (Air France from Paris) and leave on the following Monday morning at 7:55am; staying at The Avenues Guest House.
• Jacques will arrive a whole week before, Sunday Nov. 23, stay in Cape Town, then get to Stellenbosch on Monday 1 December, and leave on Saturday Dec 6 at 5 PM (Turkish Airlines TK 45). Staying at Laanhof.
• Shraddha will arrive on 1st Dec 11.40am and leave on Sunday 7th Dec 9.30pm; staying at the 5 Seasons Guest House.
• Ohad will arrive Monday 1 Dec 11.15pm and leave Friday 5 Dec 11.45pm (KL598). His luggage will hopefully arrive the following day :(. Staying at the 5 Seasons Guest House.