Nonogram
Numbers along each edge say how the filled runs are grouped.
The maths Deduction from run-length clues
0 of 17 squares filled. 0 rows and 0 columns match their clues.
How to play
The numbers beside a row or above a column give the lengths of the filled runs in that line, in order, with at least one blank square between them. A row clue of 3 then 1 means three filled squares together, a gap, then one more filled square, with any number of blanks around them.
Click a square to fill it, click again to cross it out as definitely blank, and click a third time to clear it. Right-click goes straight to a cross, and so does the button that switches tapping between filling and crossing out. Crosses are your own notes — they are never checked, so use as many as you like.
A clue dims and is struck through once that line's filled squares match it exactly. The puzzle is done when the filled squares are precisely the hidden picture.
Keyboard: arrow keys move around the grid, Home and End jump to the first and last square, Space or Enter cycles the square under the cursor, and X crosses it out or clears the cross.
Where to start: look for a clue whose run is longer than half the line. Slide it as far left as it will go, then as far right, and any square covered both times is filled in every possible arrangement, so you can fill it with certainty.
Why this is mathematics
A clue of "5" in a row of seven does not tell you where the run starts, but it does tell you three squares must be filled whatever happens — the overlap of the leftmost and rightmost placements. Finding what is true in every possible case is exactly how a proof works.