Instances and theorems on pi types #
This file provides basic definitions and notation instances for Pi types.
Instances of more sophisticated classes are defined in Pi.lean
files elsewhere.
1
, 0
, +
, *
, +ᵥ
, •
, ^
, -
, ⁻¹
, and /
are defined pointwise.
Porting note: bit0
and bit1
are deprecated. This section can be removed entirely
(without replacement?).
The function supported at i
, with value x
there, and 0
elsewhere.
Equations
- Pi.single i x = Function.update 0 i x
Instances For
The function supported at i
, with value x
there, and 1
elsewhere.
Equations
- Pi.mulSingle i x = Function.update 1 i x
Instances For
Abbreviation for single_eq_of_ne h.symm
, for ease of use by simp
.
Abbreviation for mulSingle_eq_of_ne h.symm
, for ease of use by simp
.
On non-dependent functions, Pi.mulSingle
can be expressed as an ite
On non-dependent functions, Pi.single
is symmetric in the two indices.
On non-dependent functions, Pi.mulSingle
is symmetric in the two indices.
If the zero function is surjective, the codomain is trivial.
Equations
Instances For
If the one function is surjective, the codomain is trivial.