An upright T shape with the crossbar at the foot, stating that two lines meet at a right angle.
Also known as: Up tack, Upside-down T
⊥ states that two lines or planes meet at a right angle. The same character is also used in logic for a contradiction and in lattice theory for a bottom element — three unrelated meanings sharing one shape.
Is encoded as U+22A5 UP TACK in the Mathematical Operators block.
Contexts: Mathematics
States in geometry that two lines, or a line and a plane, meet at a right angle.
Contexts: Mathematics
Denotes falsity or a contradiction in formal logic, and the bottom element in lattice and domain theory — meanings unrelated to the geometric one that happen to share the character.
Contexts: Mathematics
A horizontal bar sitting on the writing line with a vertical stroke rising from its centre, forming a capital T turned upside down.
Lines meeting at a right angle, against lines that never meet.