Topology of fitting duvet covers

When I was still a teen, grandma showed me a very clever way to fit a cover onto a duvet. She tried to teach me but I didn't manage to do it at that time. A few months ago I was fitting my duvet with its cover after laundry, I thought really hard of it. With a lot of thinking and practice, I finally did it and now I write it down here in my own words.

1. Spread the cover over a bed inside out.
2. Put the duvet on top of the cover, align the four corners.
3. Starting from the far end, roll the cover and the duvet together toward the opening edge of the cover. You will end up with a roll of duvet laminated by the cover on the outer side.
4. At the opening edge, grab the two corners of the duvet at the aligned corners of the cover from INSIDE.
5. Stuff the edge of the duvet bracketed by these two corners into the cover.
6. Repeat rolling the laminated duvet all the way till you reach the opening edge of the cover again.
7. Grab the 2 corners, spread the duvet and you will have the cover fitted tight at the corners.

It was magic to me when I first saw grandma did it. After all the years I figured she had solve a 2-dimensional problem by 3-dimensional topology! A few months ago when I finally got to do it on my own, I asked grandma who taught her this. She said she figured it out herself.

I always tell people grandma is very smart.

Grandma

I missed grandma very much today. I called her up and we talked for over 20 min.

I used to be very closed to her. My mom needed to work and grandma was the one who looked after me since I was born. She hefted me on her back to the market everyday when I was a toddler. She taught me what was right, what was wrong; how to behave and how to respect people.

A few years ago she needed to implant a heartbeat regulator onto her heart. I flew to see her and stayed with her in the hospital. I held her hands the first time since I grew up. The doctor said she was strong and healthy otherwise. She recovered very quickly and only stayed in the hospital for 3 days after the surgery. I was relieved.

Grandma is a very smart and clever woman. She made many important decisions for our family that were proved to be correct. I always think if she had had the chance to go to school, she would have had a great career. But she would probably not be my grandma.

I am very lucky to have a great woman guide me throughout my childhood. You gave me all it takes to make me a decent human being. Although we are not related by blood, your teaching and love always flow in my blood. I love you, Grandma.

Grandma, my mom's sister and me in Edinburg Square,
Hong Kong, 1977.