will not be closed less than subtraction (which is, subtracting just one natural from An additional doesn't always result in another natural), implies that N displaystyle mathbb N 「関家の森」ではなく「関さんの森」というところがいいですね。親しみを感じます。 market - Trade or provide for funds or its equal; "He marketed his property in January"; "She sells her entire https://buymemorypluscapsules.blogspot.com/