Expression of type Equals

from the theory of proveit.logic.equality

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 Conditional, ExprRange, Function, Lambda, Variable, alpha, beta, n, theta
from proveit.core_expr_types import Len
from proveit.logic import Equals, InSet
from proveit.numbers import Natural, one, two

# build up the expression from sub-expressions
sub_expr1 = Variable("_a", latex_format = r"{_{-}a}")
expr = Equals(Len(operands = [[alpha, beta], Lambda(n, Conditional(Function(theta, [n]), InSet(n, Natural)))]), Len(operands = [ExprRange(sub_expr1, sub_expr1, one, 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(\left(\alpha, \beta\right), n \mapsto \left\{\theta\left(n\right) \textrm{ if } n \in \mathbb{N}\right..\right)| = |\left(1, \ldots, 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',)
direction	Direction of the relation (normal or reversed)	normal	normal	('with_direction_reversed', 'is_reversed')

# 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
3	Operation	operator: 6 operands: 5
4	Operation	operator: 6 operands: 7
5	ExprTuple	8, 9
6	Literal
7	ExprTuple	10
8	ExprTuple	11, 12
9	Lambda	parameter: 25 body: 13
10	ExprRange	lambda_map: 14 start_index: 15 end_index: 16
11	Variable
12	Variable
13	Conditional	value: 17 condition: 18
14	Lambda	parameter: 24 body: 24
15	Literal
16	Literal
17	Operation	operator: 20 operand: 25
18	Operation	operator: 22 operands: 23
19	ExprTuple	24
20	Variable
21	ExprTuple	25
22	Literal
23	ExprTuple	25, 26
24	Variable
25	Variable
26	Literal