Expression of type Len

from the theory of proveit.core_expr_types.tuples

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 ExprRange, IndexedVar, Variable, n, x
from proveit.core_expr_types import Len
from proveit.numbers import Add, one, subtract, zero

# build up the expression from sub-expressions
sub_expr1 = Variable("_a", latex_format = r"{_{-}a}")
expr = Len(operands = [ExprRange(sub_expr1, IndexedVar(x, Add(sub_expr1, one)), zero, subtract(n, one))])

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(x_{0 + 1}, x_{1 + 1}, \ldots, x_{\left(n - 1\right) + 1}\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
3	ExprRange	lambda_map: 4 start_index: 5 end_index: 6
4	Lambda	parameter: 19 body: 8
5	Literal
6	Operation	operator: 17 operands: 9
7	ExprTuple	19
8	IndexedVar	variable: 10 index: 14
9	ExprTuple	12, 13
10	Variable
11	ExprTuple	14
12	Variable
13	Operation	operator: 15 operand: 20
14	Operation	operator: 17 operands: 18
15	Literal
16	ExprTuple	20
17	Literal
18	ExprTuple	19, 20
19	Variable
20	Literal