Expression of type Len

from the theory of proveit.numbers.numerals.decimals

import proveit
# Automation is not needed when building an expression:
proveit.defaults.automation = False # This will speed things up.
proveit.defaults.inline_pngs = False # Makes files smaller.
%load_expr # Load the stored expression as 'stored_expr'
# import Expression classes needed to build the expression
from proveit import Lambda, Variable
from proveit.core_expr_types import Len
from proveit.numbers import eight, five, four, nine, seven, six, three, two

# build up the expression from sub-expressions
sub_expr1 = Variable("_b", latex_format = r"{_{-}b}")
sub_expr2 = Lambda(sub_expr1, seven)
expr = Len(operands = [Lambda(sub_expr1, three), Lambda(sub_expr1, eight), Lambda(sub_expr1, six), sub_expr2, Lambda(sub_expr1, four), Lambda(Variable("_a", latex_format = r"{_{-}a}"), nine), Lambda(sub_expr1, five), sub_expr2, Lambda(sub_expr1, two)])

expr:

# check that the built expression is the same as the stored expression
assert expr == stored_expr
assert expr._style_id == stored_expr._style_id
print("Passed sanity check: expr matches stored_expr")

Passed sanity check: expr matches stored_expr

# Show the LaTeX representation of the expression for convenience if you need it.
print(stored_expr.latex())

|\left({_{-}b} \mapsto 3, {_{-}b} \mapsto 8, {_{-}b} \mapsto 6, {_{-}b} \mapsto 7, {_{-}b} \mapsto 4, {_{-}a} \mapsto 9, {_{-}b} \mapsto 5, {_{-}b} \mapsto 7, {_{-}b} \mapsto 2\right)|

stored_expr.style_options()

name	description	default	current value	related methods
operation	'infix' or 'function' style formatting	infix	infix
wrap_positions	position(s) at which wrapping is to occur; '2 n - 1' is after the nth operand, '2 n' is after the nth operation.	()	()	('with_wrapping_at', 'with_wrap_before_operator', 'with_wrap_after_operator', 'without_wrapping', 'wrap_positions')
justification	if any wrap positions are set, justify to the 'left', 'center', or 'right'	center	center	('with_justification',)

# display the expression information
stored_expr.expr_info()

	core type	sub-expressions	expression
0	Operation	operator: 1 operands: 2
1	Literal
2	ExprTuple	3, 4, 5, 9, 6, 7, 8, 9, 10
3	Lambda	parameter: 22 body: 11
4	Lambda	parameter: 22 body: 12
5	Lambda	parameter: 22 body: 13
6	Lambda	parameter: 22 body: 14
7	Lambda	parameter: 21 body: 16
8	Lambda	parameter: 22 body: 17
9	Lambda	parameter: 22 body: 18
10	Lambda	parameter: 22 body: 20
11	Literal
12	Literal
13	Literal
14	Literal
15	ExprTuple	21
16	Literal
17	Literal
18	Literal
19	ExprTuple	22
20	Literal
21	Variable
22	Variable