Expression of type Lambda

from the theory of proveit.logic.sets.enumeration

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, Lambda, x
from proveit.core_expr_types import y_1_to_n
from proveit.logic import InSet, Set
from proveit.logic.sets import x_equals_any_y

# build up the expression from sub-expressions
expr = Lambda([x, y_1_to_n], Conditional(x_equals_any_y, InSet(x, Set(y_1_to_n))))

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, y_{1}, y_{2}, \ldots, y_{n}\right) \mapsto \left\{\left(x = y_{1}\right) \lor  \left(x = y_{2}\right) \lor  \ldots \lor  \left(x = y_{n}\right) \textrm{ if } x \in \left\{y_{1}, y_{2}, \ldots, y_{n}\right\}\right..

stored_expr.style_options()

no style options

# display the expression information
stored_expr.expr_info()

	core type	sub-expressions	expression
0	Lambda	parameters: 1 body: 2
1	ExprTuple	21, 15
2	Conditional	value: 3 condition: 4
3	Operation	operator: 5 operands: 6
4	Operation	operator: 7 operands: 8
5	Literal
6	ExprTuple	9
7	Literal
8	ExprTuple	21, 10
9	ExprRange	lambda_map: 11 start_index: 19 end_index: 20
10	Operation	operator: 12 operands: 13
11	Lambda	parameter: 25 body: 14
12	Literal
13	ExprTuple	15
14	Operation	operator: 16 operands: 17
15	ExprRange	lambda_map: 18 start_index: 19 end_index: 20
16	Literal
17	ExprTuple	21, 22
18	Lambda	parameter: 25 body: 22
19	Literal
20	Variable
21	Variable
22	IndexedVar	variable: 23 index: 25
23	Variable
24	ExprTuple	25
25	Variable