# from the theory of proveit.numbers.addition.subtraction¶

In [1]:
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, ExprTuple, Lambda, a, b
from proveit.numbers import greater_eq, subtract, zero

In [2]:
# build up the expression from sub-expressions
expr = ExprTuple(Lambda([a, b], Conditional(greater_eq(subtract(a, b), zero), greater_eq(a, b))))

expr:
In [3]:
# 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

In [4]:
# Show the LaTeX representation of the expression for convenience if you need it.
print(stored_expr.latex())

\left(\left(a, b\right) \mapsto \left\{\left(a - b\right) \geq 0 \textrm{ if } a \geq b\right..\right)

In [5]:
stored_expr.style_options()

no style options
In [6]:
# display the expression information
stored_expr.expr_info()

core typesub-expressionsexpression
0ExprTuple1
1Lambdaparameters: 2
body: 3
2ExprTuple13, 17
3Conditionalvalue: 4
condition: 5
4Operationoperator: 7
operands: 6
5Operationoperator: 7
operands: 8
6ExprTuple9, 10
7Literal
8ExprTuple17, 13
9Literal
10Operationoperator: 11
operands: 12
11Literal
12ExprTuple13, 14
13Variable
14Operationoperator: 15
operand: 17
15Literal
16ExprTuple17
17Variable