Barbara Fantechi
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barbarafantechi.bsky.social
Barbara Fantechi
@barbarafantechi.bsky.social
1.6K followers 380 following 3.2K posts
Mathematician, cis woman, bi, het married, parent of adults. Loud in the physical and metaphorical sense.

https://marginalnotesmaths.blogspot.com/
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barbarafantechi.bsky.social
I now found a thinner non black marker! As you can see, every order extra is an extra little arrow. If I am in an artistic mood I can also draw (x^4,y-x^2,z-x^3) for a 3D effect.
Using the same method as the previous picture, this time the drawings are done with black and red pen, both equally thin. (x ³, y ²-x) is represented by two very short red arrows; the first points horizontally to the right at the origin, and the second starts at the tip of the first and curves upwards. (x ⁴ ,y ²-x) is represented by three very short red arrows; the first and second as above, and the third starts at the tip of the second and curves further upwards.
November 15, 2025 at 1:57 PM
barbarafantechi.bsky.social
These I draw every year I teach algebraic geometry (to be honest, for the ring I use C instead of R because the students must learn to draw R and see C)
A series of six drawings, in green and black on whiteboard. Each includes a ring, of the form R[x,y] modulo some generators, and a drawing of the coordinate axes in black and of a no reduced scheme in green. The six generator sets & drawings x ², y & a short horizontal segment center ed on zero on the x axis x ³, y-x ² & a short, but less short, segment of the parabola y-x ²=0 centered at the origin x ²,y ² & a tiny square centered at the origin x ²,y ²,xy & a tinier square centered at the origin and rotated by 45° (y-1) ² & a thickened line y=1 (y-1)((x+2), (y-1) ² & the line y=1 and a tiny vertical segment sticking out at (-2,1)
November 14, 2025 at 9:51 PM
barbarafantechi.bsky.social
Excellent drawing!
A white and cappuccino coloured cat with espresso colour details (ears, eye ask, nose and tail) lies on a bed with a purple bedclothes and pale blue blanket and throw pillows. He looks mildly annoyed.
November 14, 2025 at 9:33 PM
barbarafantechi.bsky.social
Ball with headlights
A poorly focused picture of a cat, curled up in a semi spherical depression in a cat tree. The tip of the tail touches the tip of the left ear. The right eye is open and reflects the light if the flash.
November 12, 2025 at 6:47 PM
barbarafantechi.bsky.social
Usually the best part of my commute is the walk at the end (see photo).

Today however the bus was full of primary school kids, and halfway up the hill they started singing Sofia by Àlvaro Soler.
I am in my office now and I am still smiling. I may have tanked energy for the whole day.
On a very sunny day, a view of Trieste coastline looking towards Slovenia, from high up on the Karst. The view is framed by nearby slowly yellowing trees.
November 11, 2025 at 8:52 AM
barbarafantechi.bsky.social
No cat has been harmed for this picture.

Buona domenica!
A person dressed in pajamas sits on an office chair covered with cute fleece blankets. In their lap lies in his right side a large cat, who is yawning so we can see his mouth wide open. The hand of a different person can be seen touching the cat on his lower belly: the cat keeps his hind legs open to give better access.
November 9, 2025 at 1:57 PM
barbarafantechi.bsky.social
I managed to keep a daily diary for a full year. A very small diary, but a diary nevertheless. Very useful as my memory never fully recovered from the depression years.

NB I had bought this notebook in early 2021, but soon lost it. A year ago I found it again.
Poor quality photo of a blue notebook, embossed with the writing Some lines a day (write, cursive) The 5 year notebook (black, small caps) One can glimpse an elastic band to keep the notebook closed, and two cloth bookmarks, one dark blue and one grey.
October 31, 2025 at 9:57 PM
barbarafantechi.bsky.social
Home from work, eldest is out to buy cat food, so sitting on her chair to give cat a warm place to lie down on.
Same cat I always post lying on my thighs as I sit down, looking away from me. On the floor are two home shoes.
October 27, 2025 at 4:53 PM
barbarafantechi.bsky.social
Does the café also have Kuchen?

To get something vaguely Kuchen-adjacent I ended up buying this at a supermarket in Sežana.
A chocolate cake covered in cream with red candles cherries on top in a rigid, am transparent plastic container. A sticker on the container reads sladka stran življenja slaščice SPAR (logo of the supermarket) Ročna izdelava
October 26, 2025 at 4:09 PM
barbarafantechi.bsky.social
I followed the “get started“ advice and emptied three 50x60 cm drawers by sorting old clothes into “I might still use” “give away” “trash”.

I had meant to do this for a long while and it only took me about one hour.

Thank you!
The inside of a clothes cabinet (IKEA Pax) with wire drawers. One can see three empty drawers and a full one below.
October 26, 2025 at 11:22 AM
barbarafantechi.bsky.social
Celebrating #caturday
October 25, 2025 at 4:14 PM
barbarafantechi.bsky.social
Today I arrived early and got pictures of the cute lecture room!

I am not sure how many of the students appreciate my devoting 1 hour every 5 to examples, drawings, and elementary calculations, but I sure do!

Bonus picture: corridor with lecture rooms NOT in alphabetical order.
A lecture room seen from the back. The wall in front of us has a blackboard over all its length; in the right is a window. One can see the desks of three rows of seats. The same room from a different angle. There are four rows of wooden seats and desks at slightly degrading height so everyone can see. The windows, and thus the ceiling, are very high. A corridor with wooden benches and artificial light. On the side one can see four large wooden doors labelled in order Aula B, No Label, Aula D, Aula A.
October 23, 2025 at 12:51 PM
barbarafantechi.bsky.social
I'm back home and tonight I get to sleep in the room with the cat because the room's owner is still on vacation.
An office chair covered in a green and a pair blue-green with cherry motif blankets, on top of which lies majestically a large white, cappuccino and coffee coloured cat. All four (white socked) paws are close to each other. The cat is awake and appears to be meditating.
October 18, 2025 at 8:19 PM
barbarafantechi.bsky.social
I can't do anything helpful but you can spend a few seconds gazing on a fountain on a street close to the Vatican in Rome. No I don't know why there's a chubby dragon (the eagle is a symbol of Rome).

Bonus cat for Caturday.
A street paved with dark cobblestone and sidewalk bordered in white stone and paved with darker, smaller cobblestones. On an orange wall with visible water damage best the floor is a stone fountain with the basin in the form of a shell and the spout as the mouth of a winged chubby dragon in bas relief in an oval contour. The whole is inside a streamlined Roman temple (two columns on each side and a triangular roof), also in bas relief, and directly on top of the dragon is the imperial eagle looking up. A balcony that can be closed with windows. On a glass door leading inside the apartment, the reflection of many trees. Central on the balcony ledge lies an orange red very fluffy cat with green eyes, staring at the world with a concerned expression.
October 18, 2025 at 2:05 PM
barbarafantechi.bsky.social
I shouldn't post after mezzo litro di birra
A grey table. On top an arabet 4 indicating 876 CO2 level and a Bitburger half a liter bett can
October 12, 2025 at 5:21 PM
barbarafantechi.bsky.social
I am in an airport without a mask on.

Yes I am sitting directly next to a door which opens all the time.
A red soft bag with an aranet 4 sensor on top. The sensor shows 22C temperature, 47% humidity, and a CO2 level of 602.
October 12, 2025 at 4:05 PM
barbarafantechi.bsky.social
Greetings from the Black Forest! I am super happy because I found how to switch on the heating in my room*.

*Move the arrow from ❄️ to 2 on a scale 1 to 5
Panorama of a valley covered in grass with some deciduous trees, the hills opposite are covered by both deciduous and needle leaved trees. The sky has a summer like blue but the leaves have just started to turn yellow and brown.
October 10, 2025 at 5:51 PM
barbarafantechi.bsky.social
Q Who needs to see a picture of a cat who has regained his full winter fur and this looks particularly round?

A We all do.
#ProofOfCat
An office chair covered in fleece blankets. On it is curled up a large, cappuccino with a swirl of milk coloured cat. He covers his eyes with one paw, as if to shelter them from the bright daylight coming through the window.
October 10, 2025 at 11:47 AM
barbarafantechi.bsky.social
This morning strong wind (70kmh average 100kmh top speed) and rain, after lunch the sun came out and the wind ceased.
This was taken about 5pm, I am looking out to sea and the handsome mountains in the distance are the Alps, which means good weather all the way there.
Top half of the photo: sky with very sparse clouds on the horizon Bottom half: blue sea with tiny waves On the horizon right to left: a nearby promontory, two further ones, the latter with an industrial landscape, two sailing boats and a container ship. Behind them, grey against the blue sky, the profile of the Eastern Italian Alps (approx 250km away)
October 5, 2025 at 6:43 PM
barbarafantechi.bsky.social
Having waited near the door for the return of his human for many* hours, the poor cat has become exhausted.
#caturday

*two
On a white bench are a white sweatshirt and a purple one, the latter is nearly folded. On top of the purple shirt lies a cat in a competition circular position, the head on the forehead, almost no paw visible and only one ear and the top of the nose.
October 4, 2025 at 7:33 PM
barbarafantechi.bsky.social
The air quality at FRA is surprisingly decent.
A small round table , on top an arabet showing CO2 1043 and evaluating it as yellow (not green, note red). On the side a small bag, across the window details of an airport
October 3, 2025 at 5:19 PM
barbarafantechi.bsky.social
Wednesday afternoon in Oberwolfach's the program is "walk to the heavy and eat Black Forest Cake".
I walked almost 4 hours and 25+K steps and am very tired now.
A table with a white on white embroidered table cloth and elegant porcelain. Central is a pleasure with a big slice of cream and chocolate cake with dark cherries, at its side a large glass of opaque light brown liquid A panorama of the buildings, left to right library, main accommodation and apartments. They are modern low buildings half hidden by tea, in a sunny green valley amid hills covered by dark fir trees. The sky is very blue. A panorama from high on a hill. In the distance other hills on the other side of the valley, in fairground a donkey behind a fence.
October 1, 2025 at 7:08 PM
barbarafantechi.bsky.social
There's a nice book in Oberwolfach's library which I have no time to read while I am here, but maybe I can ask my university to buy it.

Anyone has opinions?
A book with a black cover and the drawing of two stylised snakes made of triangles. Title AI SNAKE OIL Subtitle What Artificial Intelligence Can Do, What It Can't, and How to Tell the Difference Authors Arvind Narayanan & Sayash Kapoor
October 1, 2025 at 10:08 AM
barbarafantechi.bsky.social
Oberwolfach chronicles today: of course a maths research center uses robots!
September 30, 2025 at 12:24 PM
barbarafantechi.bsky.social
One where the filling moves from under your head to around your ears.
An 80cm wide square down filled pillow, with a bunch of stuff (small backpack, books) where one's head would be. The pillow lowers under the weight and swells up at either side.
September 29, 2025 at 12:22 PM