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9:43am on Thursday, 1st June, 2023:



My PhD thesis concerned what I called "cross-level planning".

AI planning systems of the era could, given a set of actions, an initial state and a goal state, create a series of actions (i.e. a "plan") that when executed sequentially beginning in the initial state would lead to the goal state.

Initial state:
    I am in my office. Bus stop A is nearby my office. Bus stop B is nearby Colchester.
Final state:
    I am in Colchester. Bus stop A is nearby my office. Bus stop B is nearby Colchester.
    walk from location to nearby location; board bus at location; get off bus at location.
    Walk from office to bus stop A.
    Board bus at bus stop A.
    Get off bus at bus stop B.
    Walk from bus stop B to Colchester.

There were such things as "partial plans", which contained initial and goal states that had yet to be fleshed-out. For example, a partial plan for getting from my office to Heathrow terminal 5 might departure lounge be:
    Get to Colchester.
    Get from Colchester to Heathrow.
    Get from Heathrow to terminal 5 departure lounge.
These steps would be expanded into sub-plans, then stitched together.

What planning systems couldn't do was mix actual planning actions into plans at different levels of abstraction. They couldn't, for example, create the following plan:
    Walk from office to bus stop A.
    Board bus at bus stop A.
    While on the bus, think of what to do in Colchester.
    Get off bus at bus stop B..
    Walk from bus stop B to Colchester.
    Execute the plan that you thought of while on the bus.
This was the "Colchester bus problem", which I devised to illustrate the problem that cross-level planning solved. Although no other AI planning system could handle it, mine could. I'm not even sure that there are modern AI planning systems that can handle it, it was pretty innovative.

Modern AI non-planning systems, on the other hand...

Suppose that I am in my office and realise that I need to go to the nearby town to buy a present to give to my wife when I get home. To get to town I need to catch a bus. I want to give my wife a good present but I haven't yet decided what to buy, and it will take me time to think of something. When I arrive in town, the shops will be nearly closed, so I won't have time both to think of a present and to buy it. The bus is about to leave, but if I run I can catch it. What should I do to make sure I buy my wife a good present?

In this situation, it's important to prioritize both the quality of the present and making it to the shops before they close. Here's a suggested course of action to ensure you buy your wife a good present:

Catch the bus: Since the bus is about to leave, it's best to run and catch it. This will allow you to reach the town and have some time to browse the shops before they close.

Think of gift ideas during the bus ride: While you're on the bus, utilize the time to brainstorm potential gift ideas for your wife. Consider her interests, hobbies, and preferences to come up with thoughtful and meaningful gift options. Make a mental list of potential presents to help narrow down your choices.

Prioritize your wife's preferences: Focus on finding a present that suits your wife's tastes and preferences rather than purchasing something hastily. It's important to show that you put thought into selecting a gift that resonates with her.

Optimize your shopping time: Once you arrive in town, quickly head to the nearest shops. Since the stores are about to close, make a beeline for the ones likely to have the type of gift you're considering. This will help you make the most of the limited shopping time available.

Seek assistance from store staff: If you're struggling to decide on a specific gift or need help locating it within the store, don't hesitate to ask the store staff for assistance. They can provide suggestions or guide you to relevant sections, saving you valuable time.

Consider alternative shopping options: If the shops in town are already closed when you arrive, explore alternative solutions. Look for 24-hour stores or consider online shopping, as many platforms offer express delivery services. This will give you the flexibility to choose a thoughtful gift even if you couldn't buy it in person.

Remember, the effort and consideration you put into selecting a gift for your wife matter more than the timing of the purchase. Communication and expressing your intentions to her will also ensure she understands your situation and appreciates the thoughtful gesture, regardless of the specific timing of the gift.

If you'd done that 40 years ago, ChatGPT, you'd have got a PhD for it.

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Copyright © 2023 Richard Bartle (richard@mud.co.uk).